diff --git a/compiler+runtime/CMakeLists.txt b/compiler+runtime/CMakeLists.txt
index 42e1382d4..2809c8f42 100644
--- a/compiler+runtime/CMakeLists.txt
+++ b/compiler+runtime/CMakeLists.txt
@@ -42,6 +42,7 @@ option(jank_coverage "Enable code coverage measurement" OFF)
 option(jank_analyze "Enable static analysis" OFF)
 option(jank_test "Enable jank's test suite" OFF)
 option(jank_unity_build "Optimize translation unit compilation for the number of cores" OFF)
+option(jank_debug_gc "Enable GC debug assertions" OFF)
 set(jank_sanitize "none" CACHE STRING "The type of Clang sanitization to use (or none)")
 set(jank_resource_dir
   "../lib/jank/${CMAKE_PROJECT_VERSION}"
diff --git a/compiler+runtime/cmake/dependency/bdwgc.cmake b/compiler+runtime/cmake/dependency/bdwgc.cmake
index fff5b9cba..a0b897c78 100644
--- a/compiler+runtime/cmake/dependency/bdwgc.cmake
+++ b/compiler+runtime/cmake/dependency/bdwgc.cmake
@@ -2,8 +2,8 @@ set(CMAKE_C_FLAGS_OLD "${CMAKE_C_FLAGS}")
 set(CMAKE_CXX_FLAGS_OLD "${CMAKE_CXX_FLAGS}")
 set(BUILD_SHARED_LIBS_OLD ${BUILD_SHARED_LIBS})
 set(CMAKE_CXX_CLANG_TIDY_OLD ${CMAKE_CXX_CLANG_TIDY})
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w -DREDIRECT_MALLOC=GC_malloc_uncollectable")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w -DREDIRECT_MALLOC=GC_malloc_uncollectable")
   set(BUILD_SHARED_LIBS OFF)
   set(CMAKE_CXX_CLANG_TIDY "")
   set(enable_cplusplus ON CACHE BOOL "Enable C++")
@@ -11,11 +11,22 @@ set(CMAKE_CXX_CLANG_TIDY_OLD ${CMAKE_CXX_CLANG_TIDY})
   set(enable_docs OFF CACHE BOOL "Enable docs")
   set(enable_large_config ON CACHE BOOL "Optimize for large heap or root set")
   set(enable_throw_bad_alloc_library ON CACHE BOOL "Enable C++ gctba library build")
+  set(enable_gc_debug OFF CACHE BOOL "Support for pointer back-tracing")
+
+  if(jank_debug_gc)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DGC_ASSERTIONS")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DGC_ASSERTIONS")
+    set(enable_gc_debug ON CACHE BOOL "Support for pointer back-tracing")
+  endif()
+
   add_subdirectory(third-party/bdwgc EXCLUDE_FROM_ALL)
 
   unset(enable_cplusplus)
   unset(build_cord)
   unset(enable_docs)
+  unset(enable_large_config)
+  unset(enable_throw_bad_alloc_library)
+  unset(enable_gc_debug)
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS_OLD}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_OLD}")
 set(BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS_OLD})
diff --git a/compiler+runtime/include/cpp/jank/codegen/llvm_processor.hpp b/compiler+runtime/include/cpp/jank/codegen/llvm_processor.hpp
index c5688b954..803918ac1 100644
--- a/compiler+runtime/include/cpp/jank/codegen/llvm_processor.hpp
+++ b/compiler+runtime/include/cpp/jank/codegen/llvm_processor.hpp
@@ -110,7 +110,7 @@ namespace jank::codegen
                    compilation_target target);
     /* For this ctor, we're inheriting the context from another function, which means
      * we're building a nested function. */
-    llvm_processor(analyze::expr::function_ref expr, std::unique_ptr<reusable_context> ctx);
+    llvm_processor(analyze::expr::function_ref expr, jtl::ref<reusable_context> ctx);
     llvm_processor(llvm_processor const &) = delete;
     llvm_processor(llvm_processor &&) noexcept = default;
 
diff --git a/compiler+runtime/include/cpp/jank/read/parse.hpp b/compiler+runtime/include/cpp/jank/read/parse.hpp
index 8de1c5e14..e42d364d4 100644
--- a/compiler+runtime/include/cpp/jank/read/parse.hpp
+++ b/compiler+runtime/include/cpp/jank/read/parse.hpp
@@ -117,7 +117,7 @@ namespace jank::read::parse
      * token, we should check this list to see if there's already a form we should pull out.
      * This is needed because parse iteration works one form at a time and splicing potentially
      * turns one form into many. */
-    std::list<runtime::object_ref> pending_forms;
+    native_list<runtime::object_ref> pending_forms;
     lex::token latest_token;
     jtl::option<shorthand_function_details> shorthand;
     /* Whether or not the next form is considered quoted. */
diff --git a/compiler+runtime/include/cpp/jank/runtime/context.hpp b/compiler+runtime/include/cpp/jank/runtime/context.hpp
index 0f23616f1..c1ac657ff 100644
--- a/compiler+runtime/include/cpp/jank/runtime/context.hpp
+++ b/compiler+runtime/include/cpp/jank/runtime/context.hpp
@@ -43,7 +43,6 @@ namespace jank::runtime
     context();
     context(context const &) = delete;
     context(context &&) noexcept = delete;
-    ~context();
 
     ns_ref intern_ns(jtl::immutable_string const &);
     ns_ref intern_ns(obj::symbol_ref const &);
@@ -161,8 +160,8 @@ namespace jank::runtime
     /* Hold onto the CLI Options for use at runtime */
     util::cli::options opts;
 
-    /* TODO: Remove this map. Just use the list. */
-    static thread_local native_unordered_map<context const *, std::list<thread_binding_frame>>
+    /* XXX: We can't use thread_local here, due to bdwgc not supporting it. */
+    static native_unordered_map<std::thread::id, native_list<thread_binding_frame>>
       thread_binding_frames;
 
     /* This must go last, since it'll try to access other bits in the runtime context during
diff --git a/compiler+runtime/include/cpp/jank/runtime/detail/type.hpp b/compiler+runtime/include/cpp/jank/runtime/detail/type.hpp
index 8eab57d00..a115e6602 100644
--- a/compiler+runtime/include/cpp/jank/runtime/detail/type.hpp
+++ b/compiler+runtime/include/cpp/jank/runtime/detail/type.hpp
@@ -8,9 +8,6 @@
 #include <immer/set_transient.hpp>
 #include <immer/memory_policy.hpp>
 
-#include <bpptree/bpptree.hpp>
-#include <bpptree/ordered.hpp>
-
 #include <jank/runtime/object.hpp>
 #include <jank/runtime/detail/native_persistent_list.hpp>
 
@@ -36,15 +33,6 @@ namespace immer
                                    jank::memory_policy>;
 }
 
-namespace bpptree::detail
-{
-  extern template struct BppTreeSet<jank::runtime::object_ref,
-                                    jank::runtime::detail::object_ref_compare>;
-  extern template struct BppTreeMap<jank::runtime::object_ref,
-                                    jank::runtime::object_ref,
-                                    jank::runtime::detail::object_ref_compare>;
-}
-
 namespace jank::runtime::detail
 {
   using native_persistent_vector = immer::vector<object_ref, memory_policy>;
@@ -54,11 +42,10 @@ namespace jank::runtime::detail
     set<object_ref, std::hash<object_ref>, std::equal_to<jank::runtime::object_ref>, memory_policy>;
   using native_transient_hash_set = native_persistent_hash_set::transient_type;
 
-  /* TODO: These BppTree types will leak until we get them GC allocated. */
+  /* TODO: Bring in proper immutable sorted maps/sets. */
   using native_persistent_sorted_set
-    = bpptree::BppTreeSet<object_ref, object_ref_compare>::Persistent;
-  using native_transient_sorted_set
-    = bpptree::BppTreeSet<object_ref, object_ref_compare>::Transient;
+    = std::set<object_ref, object_ref_compare, native_allocator<object_ref>>;
+  using native_transient_sorted_set = native_persistent_sorted_set;
 
   using native_persistent_hash_map = immer::map<object_ref,
                                                 object_ref,
@@ -68,9 +55,11 @@ namespace jank::runtime::detail
   using native_transient_hash_map = native_persistent_hash_map::transient_type;
 
   using native_persistent_sorted_map
-    = bpptree::BppTreeMap<object_ref, object_ref, object_ref_compare>::Persistent;
-  using native_transient_sorted_map
-    = bpptree::BppTreeMap<object_ref, object_ref, object_ref_compare>::Transient;
+    = std::map<object_ref,
+               object_ref,
+               object_ref_compare,
+               native_allocator<std::pair<object_ref const, object_ref>>>;
+  using native_transient_sorted_map = native_persistent_sorted_map;
 
   /* If an object requires this in its constructor, use your runtime context to intern
    * it instead. */
diff --git a/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_map.hpp b/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_map.hpp
index 97e3fdcc1..5b77e1145 100644
--- a/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_map.hpp
+++ b/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_map.hpp
@@ -18,8 +18,7 @@ namespace jank::runtime::obj
     transient_sorted_map() = default;
     transient_sorted_map(transient_sorted_map &&) noexcept = default;
     transient_sorted_map(transient_sorted_map const &) = default;
-    transient_sorted_map(runtime::detail::native_persistent_sorted_map const &d);
-    transient_sorted_map(runtime::detail::native_persistent_sorted_map &&d);
+    transient_sorted_map(value_type const &d);
     transient_sorted_map(value_type &&d);
 
     static transient_sorted_map_ref empty();
diff --git a/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_set.hpp b/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_set.hpp
index e2d679eaf..1f05fab0b 100644
--- a/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_set.hpp
+++ b/compiler+runtime/include/cpp/jank/runtime/obj/transient_sorted_set.hpp
@@ -18,8 +18,7 @@ namespace jank::runtime::obj
     transient_sorted_set() = default;
     transient_sorted_set(transient_sorted_set &&) noexcept = default;
     transient_sorted_set(transient_sorted_set const &) = default;
-    transient_sorted_set(runtime::detail::native_persistent_sorted_set const &d);
-    transient_sorted_set(runtime::detail::native_persistent_sorted_set &&d);
+    transient_sorted_set(value_type const &d);
     transient_sorted_set(value_type &&d);
 
     static transient_sorted_set_ref empty();
diff --git a/compiler+runtime/include/cpp/jank/type.hpp b/compiler+runtime/include/cpp/jank/type.hpp
index dbd3eef3a..0fb35c802 100644
--- a/compiler+runtime/include/cpp/jank/type.hpp
+++ b/compiler+runtime/include/cpp/jank/type.hpp
@@ -43,7 +43,7 @@ namespace jank
   template <typename T>
   using native_list = std::list<T, native_allocator<T>>;
   template <typename K, typename V>
-  using native_map = std::map<K, V, native_allocator<std::pair<K const, V>>>;
+  using native_map = std::map<K, V, std::less<K>, native_allocator<std::pair<K const, V>>>;
   template <typename T>
   using native_set = std::set<T, std::less<T>, native_allocator<T>>;
 
diff --git a/compiler+runtime/src/cpp/jank/analyze/processor.cpp b/compiler+runtime/src/cpp/jank/analyze/processor.cpp
index b219a91ee..95ddfe3ff 100644
--- a/compiler+runtime/src/cpp/jank/analyze/processor.cpp
+++ b/compiler+runtime/src/cpp/jank/analyze/processor.cpp
@@ -1632,7 +1632,7 @@ namespace jank::analyze
 
     native_vector<runtime::obj::symbol_ref> param_symbols;
     param_symbols.reserve(params->data.size());
-    std::set<runtime::obj::symbol> unique_param_symbols;
+    native_set<runtime::obj::symbol> unique_param_symbols;
 
     bool is_variadic{};
     for(auto it(params->data.begin()); it != params->data.end(); ++it)
@@ -2884,27 +2884,12 @@ namespace jank::analyze
     /* TODO: Detect literal and act accordingly. */
     return visit_map_like(
       [&](auto const typed_o) -> processor::expression_result {
-        using T = typename decltype(typed_o)::value_type;
-
         native_vector<std::pair<expression_ref, expression_ref>> exprs;
         exprs.reserve(typed_o->data.size());
 
         for(auto const &kv : typed_o->data)
         {
-          /* The two maps (hash and sorted) have slightly different iterators, so we need to
-           * pull out the entries differently. */
-          object_ref first{}, second{};
-          if constexpr(std::same_as<T, obj::persistent_sorted_map>)
-          {
-            auto const &entry(kv.get());
-            first = entry.first;
-            second = entry.second;
-          }
-          else
-          {
-            first = kv.first;
-            second = kv.second;
-          }
+          object_ref const first{ kv.first }, second{ kv.second };
 
           auto k_expr(analyze(first, current_frame, expression_position::value, fn_ctx, true));
           if(k_expr.is_err())
diff --git a/compiler+runtime/src/cpp/jank/c_api.cpp b/compiler+runtime/src/cpp/jank/c_api.cpp
index fd63c11ec..80e0e7d9b 100644
--- a/compiler+runtime/src/cpp/jank/c_api.cpp
+++ b/compiler+runtime/src/cpp/jank/c_api.cpp
@@ -1024,7 +1024,6 @@ extern "C"
       /* The GC needs to enabled even before arg parsing, since our native types,
        * like strings, use the GC for allocations. It can still be configured later. */
       GC_set_all_interior_pointers(1);
-      GC_enable();
       GC_init();
 
       llvm::llvm_shutdown_obj const Y{};
diff --git a/compiler+runtime/src/cpp/jank/codegen/llvm_processor.cpp b/compiler+runtime/src/cpp/jank/codegen/llvm_processor.cpp
index d606df146..d60e82064 100644
--- a/compiler+runtime/src/cpp/jank/codegen/llvm_processor.cpp
+++ b/compiler+runtime/src/cpp/jank/codegen/llvm_processor.cpp
@@ -82,7 +82,7 @@ namespace jank::codegen
          compilation_target target);
     /* For this ctor, we're inheriting the context from another function, which means
      * we're building a nested function. */
-    impl(analyze::expr::function_ref expr, std::unique_ptr<reusable_context> ctx);
+    impl(analyze::expr::function_ref expr, jtl::ref<reusable_context> ctx);
 
     jtl::string_result<void> gen();
     llvm::Value *gen(analyze::expression_ref, analyze::expr::function_arity const &);
@@ -176,10 +176,9 @@ namespace jank::codegen
     compilation_target target{};
     analyze::expr::function_ref root_fn;
     jtl::ptr<llvm::Function> llvm_fn{};
-    std::unique_ptr<reusable_context> ctx;
+    jtl::ref<reusable_context> ctx;
     native_unordered_map<obj::symbol_ref, jtl::ptr<llvm::Value>> locals;
-    /* TODO: Use gc allocator to avoid leaks. */
-    std::list<deferred_init> deferred_inits{};
+    native_list<deferred_init> deferred_inits{};
     jtl::ref<llvm::LLVMContext> llvm_ctx;
     jtl::ref<llvm::Module> llvm_module;
     jtl::ptr<llvm::BasicBlock> current_loop;
@@ -487,9 +486,8 @@ namespace jank::codegen
 
   /* Whenever we have an object in an `alloca`, we need to load it before using. This fn only
    * makes sense to use with jank objects, as opposed to native values. */
-  static llvm::Value *load_if_needed(std::unique_ptr<reusable_context> const &ctx,
-                                     llvm::Value *arg,
-                                     jtl::ptr<void> const type)
+  static llvm::Value *
+  load_if_needed(jtl::ref<reusable_context> const ctx, llvm::Value *arg, jtl::ptr<void> const type)
   {
     if(!arg)
     {
@@ -503,8 +501,7 @@ namespace jank::codegen
     return arg;
   }
 
-  static llvm::Value *
-  load_if_needed(std::unique_ptr<reusable_context> const &ctx, llvm::Value * const arg)
+  static llvm::Value *load_if_needed(jtl::ref<reusable_context> const ctx, llvm::Value * const arg)
   {
     return load_if_needed(ctx, arg, cpp_util::untyped_object_ptr_type());
   }
@@ -584,8 +581,8 @@ namespace jank::codegen
   }
 
   llvm_processor::llvm_processor(expr::function_ref const expr,
-                                 std::unique_ptr<reusable_context> ctx)
-    : _impl{ make_ref<impl>(expr, jtl::move(ctx)) }
+                                 jtl::ref<reusable_context> const ctx)
+    : _impl{ make_ref<impl>(expr, ctx) }
   {
   }
 
@@ -594,13 +591,13 @@ namespace jank::codegen
                              compilation_target const target)
     : target{ target }
     , root_fn{ expr }
-    , ctx{ std::make_unique<reusable_context>(module_name, std::make_unique<llvm::LLVMContext>()) }
+    , ctx{ make_ref<reusable_context>(module_name, std::make_unique<llvm::LLVMContext>()) }
     , llvm_ctx{ extract_context(ctx->module) }
     , llvm_module{ ctx->module.getModuleUnlocked() }
   {
   }
 
-  llvm_processor::impl::impl(expr::function_ref const expr, std::unique_ptr<reusable_context> ctx)
+  llvm_processor::impl::impl(expr::function_ref const expr, jtl::ref<reusable_context> ctx)
     : target{ compilation_target::function }
     , root_fn{ expr }
     , ctx{ std::move(ctx) }
@@ -1175,17 +1172,7 @@ namespace jank::codegen
     {
       llvm::IRBuilder<>::InsertPointGuard const guard{ *ctx->builder };
 
-      llvm_processor nested{ expr, std::move(ctx) };
-
-      /* We need to make sure to transfer ownership of the context back, even if an exception
-       * is thrown. */
-      util::scope_exit const finally{ [&]() {
-        if(nested._impl->ctx)
-        {
-          ctx = std::move(nested._impl->ctx);
-        }
-      } };
-
+      llvm_processor const nested{ expr, ctx };
       auto const res{ nested.gen() };
       if(res.is_err())
       {
@@ -1193,10 +1180,6 @@ namespace jank::codegen
         res.expect_ok();
       }
 
-      /* This is covered by finally, but clang-tidy can't figure that out, so we have
-       * to make this more clear. */
-      ctx = std::move(nested._impl->ctx);
-
       global_rtti.insert(nested._impl->global_rtti.begin(), nested._impl->global_rtti.end());
     }
 
diff --git a/compiler+runtime/src/cpp/jank/read/lex.cpp b/compiler+runtime/src/cpp/jank/read/lex.cpp
index dd71dab54..1e8339cce 100644
--- a/compiler+runtime/src/cpp/jank/read/lex.cpp
+++ b/compiler+runtime/src/cpp/jank/read/lex.cpp
@@ -1081,7 +1081,7 @@ namespace jank::read::lex
               return error::lex_invalid_number(
                 util::format(
                   "Characters '{}' are invalid for a base {} number.",
-                  jtl::immutable_string_view{ invalid_digits.begin(), invalid_digits.end() },
+                  jtl::immutable_string_view{ invalid_digits.data(), invalid_digits.size() },
                   radix),
                 { token_start, pos });
             }
diff --git a/compiler+runtime/src/cpp/jank/read/parse.cpp b/compiler+runtime/src/cpp/jank/read/parse.cpp
index a26697384..d3ca61ede 100644
--- a/compiler+runtime/src/cpp/jank/read/parse.cpp
+++ b/compiler+runtime/src/cpp/jank/read/parse.cpp
@@ -409,7 +409,7 @@ namespace jank::read::parse
 
         parsed_keys.insert({ key.ptr, key });
 
-        if constexpr(std::same_as<T, runtime::detail::native_array_map>)
+        if constexpr(jtl::is_same<T, runtime::detail::native_array_map>)
         {
           map.insert_or_assign(key.ptr, value.unwrap().ptr);
         }
@@ -435,7 +435,7 @@ namespace jank::read::parse
 
       return object_source_info{ make_box<obj::persistent_array_map>(
                                    source_to_meta(start_token.start, latest_token.end),
-                                   std::move(map)),
+                                   jtl::move(map)),
                                  start_token,
                                  latest_token };
     }
@@ -453,7 +453,7 @@ namespace jank::read::parse
 
       return object_source_info{ make_box<obj::persistent_hash_map>(
                                    source_to_meta(start_token.start, latest_token.end),
-                                   std::move(map)),
+                                   jtl::move(map)),
                                  start_token,
                                  latest_token };
     }
@@ -538,7 +538,7 @@ namespace jank::read::parse
     auto meta_result(visit_object(
       [&](auto const typed_val) -> processor::object_result {
         using T = typename decltype(typed_val)::value_type;
-        if constexpr(std::same_as<T, obj::keyword>)
+        if constexpr(jtl::is_same<T, obj::keyword>)
         {
           return object_source_info{ obj::persistent_array_map::create_unique(typed_val, jank_true),
                                      start_token,
@@ -683,7 +683,7 @@ namespace jank::read::parse
     expected_closer = prev_expected_closer;
     return object_source_info{ make_box<obj::persistent_hash_set>(
                                  source_to_meta(start_token.start, latest_token.end),
-                                 std::move(ret).persistent()),
+                                 jtl::move(ret).persistent()),
                                start_token,
                                latest_token };
   }
@@ -1314,7 +1314,7 @@ namespace jank::read::parse
         [&](auto const typed_form) -> jtl::result<object_ref, error_ref> {
           using T = typename decltype(typed_form)::value_type;
 
-          if constexpr(std::same_as<T, obj::persistent_vector>)
+          if constexpr(jtl::is_same<T, obj::persistent_vector>)
           {
             auto const seq(typed_form->seq());
             if(seq.is_nil())
diff --git a/compiler+runtime/src/cpp/jank/runtime/context.cpp b/compiler+runtime/src/cpp/jank/runtime/context.cpp
index 09db0d7f8..3af7ab700 100644
--- a/compiler+runtime/src/cpp/jank/runtime/context.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/context.cpp
@@ -35,7 +35,7 @@
 namespace jank::runtime
 {
   /* NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables) */
-  thread_local decltype(context::thread_binding_frames) context::thread_binding_frames{};
+  decltype(context::thread_binding_frames) context::thread_binding_frames{};
 
   /* NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables) */
   context *__rt_ctx{};
@@ -94,11 +94,6 @@ namespace jank::runtime
       .expect_ok();
   }
 
-  context::~context()
-  {
-    thread_binding_frames.erase(this);
-  }
-
   obj::symbol_ref context::qualify_symbol(obj::symbol_ref const &sym) const
   {
     obj::symbol_ref qualified_sym{ sym };
@@ -190,7 +185,7 @@ namespace jank::runtime
       auto const name{ module::module_to_load_function(module) };
 
       auto const form{ runtime::conj(
-        runtime::conj(runtime::conj(make_box<obj::native_vector_sequence>(std::move(forms)),
+        runtime::conj(runtime::conj(make_box<obj::native_vector_sequence>(jtl::move(forms)),
                                     obj::persistent_vector::empty()),
                       make_box<obj::symbol>(name)),
         make_box<obj::symbol>("fn*")) };
@@ -705,7 +700,7 @@ namespace jank::runtime
   jtl::string_result<void> context::push_thread_bindings()
   {
     auto bindings(obj::persistent_hash_map::empty());
-    auto &tbfs(thread_binding_frames[this]);
+    auto &tbfs(thread_binding_frames[std::this_thread::get_id()]);
     if(!tbfs.empty())
     {
       bindings = tbfs.front().bindings;
@@ -734,7 +729,7 @@ namespace jank::runtime
   context::push_thread_bindings(obj::persistent_hash_map_ref const bindings)
   {
     thread_binding_frame frame{ obj::persistent_hash_map::empty() };
-    auto &tbfs(thread_binding_frames[this]);
+    auto &tbfs(thread_binding_frames[std::this_thread::get_id()]);
     if(!tbfs.empty())
     {
       frame.bindings = tbfs.front().bindings;
@@ -777,7 +772,7 @@ namespace jank::runtime
 
   jtl::string_result<void> context::pop_thread_bindings()
   {
-    auto &tbfs(thread_binding_frames[this]);
+    auto &tbfs(thread_binding_frames[std::this_thread::get_id()]);
     if(tbfs.empty())
     {
       return err("Mismatched thread binding pop");
@@ -790,7 +785,7 @@ namespace jank::runtime
 
   obj::persistent_hash_map_ref context::get_thread_bindings() const
   {
-    auto const &tbfs(thread_binding_frames[this]);
+    auto const &tbfs(thread_binding_frames[std::this_thread::get_id()]);
     if(tbfs.empty())
     {
       return obj::persistent_hash_map::empty();
@@ -800,7 +795,7 @@ namespace jank::runtime
 
   jtl::option<thread_binding_frame> context::current_thread_binding_frame()
   {
-    auto &tbfs(thread_binding_frames[this]);
+    auto &tbfs(thread_binding_frames[std::this_thread::get_id()]);
     if(tbfs.empty())
     {
       return none;
diff --git a/compiler+runtime/src/cpp/jank/runtime/detail/type.cpp b/compiler+runtime/src/cpp/jank/runtime/detail/type.cpp
index cd8a24c82..b8c4abafd 100644
--- a/compiler+runtime/src/cpp/jank/runtime/detail/type.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/detail/type.cpp
@@ -22,11 +22,3 @@ namespace immer
                             std::equal_to<jank::runtime::object_ref>,
                             jank::memory_policy>;
 }
-
-namespace bpptree::detail
-{
-  template struct BppTreeSet<jank::runtime::object_ref, jank::runtime::detail::object_ref_compare>;
-  template struct BppTreeMap<jank::runtime::object_ref,
-                             jank::runtime::object_ref,
-                             jank::runtime::detail::object_ref_compare>;
-}
diff --git a/compiler+runtime/src/cpp/jank/runtime/obj/native_vector_sequence.cpp b/compiler+runtime/src/cpp/jank/runtime/obj/native_vector_sequence.cpp
index 7603e8e3e..cea169687 100644
--- a/compiler+runtime/src/cpp/jank/runtime/obj/native_vector_sequence.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/obj/native_vector_sequence.cpp
@@ -12,13 +12,13 @@ namespace jank::runtime::obj
   }
 
   native_vector_sequence::native_vector_sequence(native_vector<object_ref> &&data)
-    : data{ std::move(data) }
+    : data{ jtl::move(data) }
   {
     jank_debug_assert(!this->data.empty());
   }
 
   native_vector_sequence::native_vector_sequence(native_vector<object_ref> &&data, usize index)
-    : data{ std::move(data) }
+    : data{ jtl::move(data) }
     , index{ index }
   {
     jank_debug_assert(!this->data.empty());
@@ -26,7 +26,7 @@ namespace jank::runtime::obj
 
   native_vector_sequence::native_vector_sequence(jtl::option<object_ref> const &meta,
                                                  native_vector<object_ref> &&data)
-    : data{ std::move(data) }
+    : data{ jtl::move(data) }
     , meta{ meta }
   {
   }
diff --git a/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_map.cpp b/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_map.cpp
index 23fbbea2d..212a26131 100644
--- a/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_map.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_map.cpp
@@ -56,9 +56,9 @@ namespace jank::runtime::obj
                                                      typed_seq->to_string()) };
             }
             auto const val(*it);
-            transient.insert_or_assign(key, val);
+            transient[key] = val;
           }
-          return transient.persistent();
+          return transient;
         }
         else
         {
@@ -100,19 +100,21 @@ namespace jank::runtime::obj
 
   bool persistent_sorted_map::contains(object_ref const key) const
   {
-    return data.find(key) != data.end();
+    return data.contains(key);
   }
 
   persistent_sorted_map_ref
   persistent_sorted_map::assoc(object_ref const key, object_ref const val) const
   {
-    auto copy(data.insert_or_assign(key, val));
+    auto copy(data);
+    copy[key] = val;
     return make_box<persistent_sorted_map>(meta, std::move(copy));
   }
 
   persistent_sorted_map_ref persistent_sorted_map::dissoc(object_ref const key) const
   {
-    auto copy(data.erase_key(key));
+    auto copy(data);
+    copy.erase(key);
     return make_box<persistent_sorted_map>(meta, std::move(copy));
   }
 
diff --git a/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_set.cpp b/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_set.cpp
index 2516fc267..283d1bef3 100644
--- a/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_set.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/obj/persistent_sorted_set.cpp
@@ -41,9 +41,9 @@ namespace jank::runtime::obj
         runtime::detail::native_transient_sorted_set transient;
         for(auto const e : make_sequence_range(typed_seq))
         {
-          transient.insert_v(e);
+          transient.insert(e);
         }
-        return transient.persistent();
+        return transient;
       },
       seq));
   }
@@ -130,8 +130,9 @@ namespace jank::runtime::obj
 
   persistent_sorted_set_ref persistent_sorted_set::conj(object_ref const head) const
   {
-    auto set(data.insert_v(head));
-    auto ret(make_box<persistent_sorted_set>(meta, std::move(set)));
+    auto copy(data);
+    copy.insert(head);
+    auto ret(make_box<persistent_sorted_set>(meta, std::move(copy)));
     return ret;
   }
 
@@ -140,7 +141,7 @@ namespace jank::runtime::obj
     auto const found(data.find(o));
     if(found != data.end())
     {
-      return found.get();
+      return *found;
     }
     return jank_nil;
   }
@@ -152,13 +153,14 @@ namespace jank::runtime::obj
 
   bool persistent_sorted_set::contains(object_ref const o) const
   {
-    return data.find(o) != data.end();
+    return data.contains(o);
   }
 
   persistent_sorted_set_ref persistent_sorted_set::disj(object_ref const o) const
   {
-    auto set(data.erase_key(o));
-    auto ret(make_box<persistent_sorted_set>(meta, std::move(set)));
+    auto copy(data);
+    copy.erase(o);
+    auto ret(make_box<persistent_sorted_set>(meta, std::move(copy)));
     return ret;
   }
 }
diff --git a/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_map.cpp b/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_map.cpp
index 7fbb68553..0629d1c22 100644
--- a/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_map.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_map.cpp
@@ -9,17 +9,12 @@
 
 namespace jank::runtime::obj
 {
-  transient_sorted_map::transient_sorted_map(runtime::detail::native_persistent_sorted_map &&d)
-    : data{ std::move(d).transient() }
-  {
-  }
-
   transient_sorted_map::transient_sorted_map(runtime::detail::native_persistent_sorted_map const &d)
-    : data{ d.transient() }
+    : data{ d }
   {
   }
 
-  transient_sorted_map::transient_sorted_map(runtime::detail::native_transient_sorted_map &&d)
+  transient_sorted_map::transient_sorted_map(runtime::detail::native_persistent_sorted_map &&d)
     : data{ std::move(d) }
   {
   }
@@ -107,14 +102,14 @@ namespace jank::runtime::obj
   transient_sorted_map::assoc_in_place(object_ref const key, object_ref const val)
   {
     assert_active();
-    data.insert_or_assign(key, val);
+    data[key] = val;
     return this;
   }
 
   transient_sorted_map_ref transient_sorted_map::dissoc_in_place(object_ref const key)
   {
     assert_active();
-    data.erase_key(key);
+    data.erase(key);
     return this;
   }
 
@@ -151,7 +146,7 @@ namespace jank::runtime::obj
   {
     assert_active();
     active = false;
-    return make_box<persistent_sorted_map>(std::move(data).persistent());
+    return make_box<persistent_sorted_map>(std::move(data));
   }
 
   object_ref transient_sorted_map::call(object_ref const o) const
diff --git a/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_set.cpp b/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_set.cpp
index 0e92a615a..1aa04f45b 100644
--- a/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_set.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/obj/transient_sorted_set.cpp
@@ -6,17 +6,12 @@
 
 namespace jank::runtime::obj
 {
-  transient_sorted_set::transient_sorted_set(runtime::detail::native_persistent_sorted_set &&d)
-    : data{ std::move(d).transient() }
-  {
-  }
-
   transient_sorted_set::transient_sorted_set(runtime::detail::native_persistent_sorted_set const &d)
-    : data{ d.transient() }
+    : data{ d }
   {
   }
 
-  transient_sorted_set::transient_sorted_set(runtime::detail::native_transient_sorted_set &&d)
+  transient_sorted_set::transient_sorted_set(runtime::detail::native_persistent_sorted_set &&d)
     : data{ std::move(d) }
   {
   }
@@ -64,7 +59,7 @@ namespace jank::runtime::obj
   transient_sorted_set_ref transient_sorted_set::conj_in_place(object_ref const elem)
   {
     assert_active();
-    data.insert_v(elem);
+    data.insert(elem);
     return this;
   }
 
@@ -72,7 +67,7 @@ namespace jank::runtime::obj
   {
     assert_active();
     active = false;
-    return make_box<persistent_sorted_set>(data.persistent());
+    return make_box<persistent_sorted_set>(data);
   }
 
   object_ref transient_sorted_set::call(object_ref const elem)
@@ -81,7 +76,7 @@ namespace jank::runtime::obj
     auto const found(data.find(elem));
     if(found != data.end())
     {
-      return found.get();
+      return *found;
     }
     return jank_nil;
   }
@@ -92,7 +87,7 @@ namespace jank::runtime::obj
     auto const found(data.find(elem));
     if(found != data.end())
     {
-      return found.get();
+      return *found;
     }
     return fallback;
   }
@@ -109,11 +104,10 @@ namespace jank::runtime::obj
 
   object_ref transient_sorted_set::get_entry(object_ref const elem)
   {
-    auto const found = call(elem);
-    auto const nil(jank_nil);
-    if(found == nil)
+    auto const found{ call(elem) };
+    if(found == jank_nil)
     {
-      return nil;
+      return found;
     }
 
     return make_box<persistent_vector>(std::in_place, found, found);
@@ -128,7 +122,7 @@ namespace jank::runtime::obj
   transient_sorted_set_ref transient_sorted_set::disjoin_in_place(object_ref const elem)
   {
     assert_active();
-    data.erase_key(elem);
+    data.erase(elem);
     return this;
   }
 
diff --git a/compiler+runtime/src/cpp/jank/runtime/var.cpp b/compiler+runtime/src/cpp/jank/runtime/var.cpp
index 44f739671..8894d37e8 100644
--- a/compiler+runtime/src/cpp/jank/runtime/var.cpp
+++ b/compiler+runtime/src/cpp/jank/runtime/var.cpp
@@ -150,7 +150,7 @@ namespace jank::runtime
       return {};
     }
 
-    auto &tbfs(__rt_ctx->thread_binding_frames[__rt_ctx]);
+    auto &tbfs(runtime::context::thread_binding_frames[std::this_thread::get_id()]);
     if(tbfs.empty())
     {
       return {};
diff --git a/compiler+runtime/src/cpp/jank/ui/highlight.cpp b/compiler+runtime/src/cpp/jank/ui/highlight.cpp
index 7c70d3812..b22afcf11 100644
--- a/compiler+runtime/src/cpp/jank/ui/highlight.cpp
+++ b/compiler+runtime/src/cpp/jank/ui/highlight.cpp
@@ -10,7 +10,7 @@ namespace jank::ui
   using namespace ftxui;
 
   /* TODO: Also support core fns? */
-  static std::set<jtl::immutable_string_view> const specials{
+  static native_set<jtl::immutable_string_view> const specials{
     "def", "fn*",   "fn",  "let*", "let",   "loop*",   "loop",  "do",
     "if",  "quote", "var", "try",  "catch", "finally", "throw", "letfn*",
   };
diff --git a/compiler+runtime/src/cpp/jank/util/try.cpp b/compiler+runtime/src/cpp/jank/util/try.cpp
index 0a4430917..c50e77d98 100644
--- a/compiler+runtime/src/cpp/jank/util/try.cpp
+++ b/compiler+runtime/src/cpp/jank/util/try.cpp
@@ -47,7 +47,7 @@ namespace jank::util
    * at the start/end of each stack trace. */
   static bool filter_frame(cpptrace::stacktrace_frame const &frame)
   {
-    static std::set<jtl::immutable_string_view> const symbols_to_ignore{
+    static native_set<jtl::immutable_string_view> const symbols_to_ignore{
       /* (Top) Linux exception pipework. */
       "get_adjusted_ptr",
       "__gxx_personality_v0",
diff --git a/compiler+runtime/third-party/bdwgc b/compiler+runtime/third-party/bdwgc
index 88a61fc6f..19a7f495c 160000
--- a/compiler+runtime/third-party/bdwgc
+++ b/compiler+runtime/third-party/bdwgc
@@ -1 +1 @@
-Subproject commit 88a61fc6f2688d8e1ea94f3f810c23db89a3f30b
+Subproject commit 19a7f495cd7c48cdf6f56c593c6dd57187afa079
diff --git a/compiler+runtime/third-party/bpptree b/compiler+runtime/third-party/bpptree
deleted file mode 160000
index addf92b02..000000000
--- a/compiler+runtime/third-party/bpptree
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit addf92b029bef74ae07f4ebb7e82312a6950ae8c