diff --git a/server/src/main/java/org/opensearch/indices/IndicesRequestCache.java b/server/src/main/java/org/opensearch/indices/IndicesRequestCache.java
index 371664dd8a64e..ed0e646dff37f 100644
--- a/server/src/main/java/org/opensearch/indices/IndicesRequestCache.java
+++ b/server/src/main/java/org/opensearch/indices/IndicesRequestCache.java
@@ -161,6 +161,7 @@ public final class IndicesRequestCache implements TieredCacheEventListener<Indic
     private final IndicesService indicesService;
     private final Settings settings;
     private final ClusterSettings clusterSettings;
+    protected final static long keyInstanceSize = RamUsageEstimator.shallowSizeOfInstance(Key.class);
 
     IndicesRequestCache(Settings settings, IndicesService indicesService, ClusterSettings clusterSettings) {
         this.size = INDICES_CACHE_QUERY_SIZE.get(settings);
@@ -459,7 +460,7 @@ interface CacheEntity extends Accountable, Writeable {
      * @opensearch.internal
      */
     class Key implements Accountable, Writeable {
-        private final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(Key.class);
+        private final long BASE_RAM_BYTES_USED = IndicesRequestCache.keyInstanceSize;
 
         public final CacheEntity entity; // use as identity equality
         public final String readerCacheKeyId;
diff --git a/server/src/main/java/org/opensearch/indices/IndicesService.java b/server/src/main/java/org/opensearch/indices/IndicesService.java
index 55ee2854ba6c0..3962bdac24e09 100644
--- a/server/src/main/java/org/opensearch/indices/IndicesService.java
+++ b/server/src/main/java/org/opensearch/indices/IndicesService.java
@@ -404,6 +404,11 @@ public class IndicesService extends AbstractLifecycleComponent
 
     private final SearchRequestStats searchRequestStats;
 
+    // Moved this computation out here to prevent recomputing the size over and over when initializing cache entities,
+    // now that IndexShardCacheEntity has to be non-static for serialization purposes
+    // (this was having significant performance impact)
+    protected static long indexShardCacheEntitySize = RamUsageEstimator.shallowSizeOfInstance(IndexShardCacheEntity.class);
+
     @Override
     protected void doStart() {
         // Start threads that will manage cleaning the field data and request caches periodically
@@ -1864,7 +1869,7 @@ private BytesReference cacheShardLevelResult(
      * @opensearch.internal
      */
     public final class IndexShardCacheEntity extends AbstractIndexShardCacheEntity {
-        private final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(IndexShardCacheEntity.class);
+        private final long BASE_RAM_BYTES_USED = IndicesService.indexShardCacheEntitySize;
         private final IndexShard indexShard;
 
         public IndexShardCacheEntity(IndexShard indexShard) {