diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b53cfcc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+crashes.json
diff --git a/debug.go b/debug.go
index 016ca46..e036d67 100644
--- a/debug.go
+++ b/debug.go
@@ -20,7 +20,7 @@ var (
 )
 
 // Debugger function.
-type DebugFunction func(string, ...interface{})
+type DebugFunction func(interface{}, ...interface{})
 
 // Terminal colors used at random.
 var colors []string = []string{
@@ -80,7 +80,7 @@ func Debug(name string) DebugFunction {
 	color := colors[rand.Intn(len(colors))]
 	prev := time.Now()
 
-	return func(format string, args ...interface{}) {
+	return func(strOrFunc interface{}, args ...interface{}) {
 		if !enabled {
 			return
 		}
@@ -89,6 +89,16 @@ func Debug(name string) DebugFunction {
 			return
 		}
 
+		var format, isString = strOrFunc.(string)
+
+		if !isString {
+			lazy, isFunc := strOrFunc.(func() string)
+			if !isFunc {
+				panic("invalid first argument type for Debug, must either be a string or lazy function")
+			}
+			format = lazy()
+		}
+
 		d := deltas(prevGlobal, prev, color)
 		fmt.Fprintf(writer, d+" \033["+color+"m"+name+"\033[0m - "+format+"\n", args...)
 		prevGlobal = time.Now()
diff --git a/debug_test.go b/debug_test.go
index 7ce2764..07dbf74 100644
--- a/debug_test.go
+++ b/debug_test.go
@@ -1,9 +1,15 @@
 package debug
 
-import "testing"
-import "strings"
-import "bytes"
-import "time"
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
 
 func assertContains(t *testing.T, str, substr string) {
 	if !strings.Contains(str, substr) {
@@ -32,6 +38,21 @@ func TestDefault(t *testing.T) {
 	}
 }
 
+func TestDefaultLazy(t *testing.T) {
+	var b []byte
+	buf := bytes.NewBuffer(b)
+	SetWriter(buf)
+
+	debug := Debug("foo")
+	debug(func() string { return "something" })
+	debug(func() string { return "here" })
+	debug(func() string { return "whoop" })
+
+	if buf.Len() != 0 {
+		t.Fatalf("buffer should be empty")
+	}
+}
+
 func TestEnable(t *testing.T) {
 	var b []byte
 	buf := bytes.NewBuffer(b)
@@ -43,6 +64,7 @@ func TestEnable(t *testing.T) {
 	debug("something")
 	debug("here")
 	debug("whoop")
+	debug(func() string { return "lazy" })
 
 	if buf.Len() == 0 {
 		t.Fatalf("buffer should have output")
@@ -52,6 +74,7 @@ func TestEnable(t *testing.T) {
 	assertContains(t, str, "something")
 	assertContains(t, str, "here")
 	assertContains(t, str, "whoop")
+	assertContains(t, str, "lazy")
 }
 
 func TestMultipleOneEnabled(t *testing.T) {
@@ -63,9 +86,11 @@ func TestMultipleOneEnabled(t *testing.T) {
 
 	foo := Debug("foo")
 	foo("foo")
+	foo(func() string { return "foo lazy" })
 
 	bar := Debug("bar")
 	bar("bar")
+	bar(func() string { return "bar lazy" })
 
 	if buf.Len() == 0 {
 		t.Fatalf("buffer should have output")
@@ -73,7 +98,9 @@ func TestMultipleOneEnabled(t *testing.T) {
 
 	str := string(buf.Bytes())
 	assertContains(t, str, "foo")
+	assertContains(t, str, "foo lazy")
 	assertNotContains(t, str, "bar")
+	assertNotContains(t, str, "bar lazy")
 }
 
 func TestMultipleEnabled(t *testing.T) {
@@ -85,9 +112,11 @@ func TestMultipleEnabled(t *testing.T) {
 
 	foo := Debug("foo")
 	foo("foo")
+	foo(func() string { return "foo lazy" })
 
 	bar := Debug("bar")
 	bar("bar")
+	bar(func() string { return "bar lazy" })
 
 	if buf.Len() == 0 {
 		t.Fatalf("buffer should have output")
@@ -95,7 +124,9 @@ func TestMultipleEnabled(t *testing.T) {
 
 	str := string(buf.Bytes())
 	assertContains(t, str, "foo")
+	assertContains(t, str, "foo lazy")
 	assertContains(t, str, "bar")
+	assertContains(t, str, "bar lazy")
 }
 
 func TestEnableDisable(t *testing.T) {
@@ -108,9 +139,11 @@ func TestEnableDisable(t *testing.T) {
 
 	foo := Debug("foo")
 	foo("foo")
+	foo(func() string { return "foo" })
 
 	bar := Debug("bar")
 	bar("bar")
+	bar(func() string { return "bar" })
 
 	if buf.Len() != 0 {
 		t.Fatalf("buffer should not have output")
@@ -143,6 +176,13 @@ func BenchmarkDisabled(b *testing.B) {
 	}
 }
 
+func BenchmarkDisabledLazy(b *testing.B) {
+	debug := Debug("something")
+	for i := 0; i < b.N; i++ {
+		debug(func() string { return "lazy" })
+	}
+}
+
 func BenchmarkNonMatch(b *testing.B) {
 	debug := Debug("something")
 	Enable("nonmatch")
@@ -150,3 +190,56 @@ func BenchmarkNonMatch(b *testing.B) {
 		debug("stuff")
 	}
 }
+
+func BenchmarkLargeNonMatch(b *testing.B) {
+	debug := Debug("large:not:lazy")
+
+	abs, _ := filepath.Abs("./crashes.json")
+	file := GetFileBytes(abs)
+
+	Enable("nonmatch")
+	for i := 0; i < b.N; i++ {
+		debug(string(file))
+	}
+}
+
+func BenchmarkLargeLazyNonMatch(b *testing.B) {
+	debug := Debug("large:lazy")
+
+	abs, _ := filepath.Abs("./crashes.json")
+	file := GetFileBytes(abs)
+
+	Enable("nonmatch")
+	for i := 0; i < b.N; i++ {
+		debug(func() string {
+			return string(file)
+		})
+	}
+}
+
+func BenchmarkLargeLazyMatch(b *testing.B) {
+	debug := Debug("large:lazy")
+
+	abs, _ := filepath.Abs("./crashes.json")
+	file := GetFileBytes(abs)
+
+	Enable("large:lazy")
+	for i := 0; i < b.N; i++ {
+		debug(func() string {
+			return string(file)
+		})
+	}
+}
+
+func GetFileBytes(filename string) []byte {
+	file, err := os.Open(filename)
+	// if we os.Open returns an error then handle it
+	if err != nil {
+		fmt.Println(err)
+	}
+	// defer the closing of our jsonFile so that we can parse it later on
+	defer file.Close()
+	bytes, _ := ioutil.ReadAll(file)
+
+	return bytes
+}
diff --git a/example/multiple.lazy.go b/example/multiple.lazy.go
new file mode 100644
index 0000000..f897529
--- /dev/null
+++ b/example/multiple.lazy.go
@@ -0,0 +1,28 @@
+package main
+
+import (
+	"time"
+
+	. "github.com/visionmedia/go-debug"
+)
+
+var a = Debug("multiple:a")
+var b = Debug("multiple:b")
+var c = Debug("multiple:c")
+
+func work(debug DebugFunction, delay time.Duration) {
+	for {
+		debug(func() string { return "doing stuff" })
+		time.Sleep(delay)
+	}
+}
+
+func main() {
+	q := make(chan bool)
+
+	go work(a, 1000*time.Millisecond)
+	go work(b, 250*time.Millisecond)
+	go work(c, 100*time.Millisecond)
+
+	<-q
+}
diff --git a/scripts/getSomeDataForPefTests.sh b/scripts/getSomeDataForPefTests.sh
new file mode 100755
index 0000000..d66d2ed
--- /dev/null
+++ b/scripts/getSomeDataForPefTests.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+curl -o crashes.json 'https://data.ny.gov/api/views/xe9x-a24f/rows.json?accessType=DOWNLOAD'