diff --git a/CHANGELOG.md b/CHANGELOG.md
index e19a0d0ed339e..35c3e91316298 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -165,6 +165,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Improve boolean parsing performance ([#11308](https://github.com/opensearch-project/OpenSearch/pull/11308))
 - Interpret byte array as primitive using VarHandles ([#11362](https://github.com/opensearch-project/OpenSearch/pull/11362))
 - Change error message when per shard document limit is breached ([#11312](https://github.com/opensearch-project/OpenSearch/pull/11312))
+- Apply the fast filter optimization to composite aggregation ([#11505](https://github.com/opensearch-project/OpenSearch/pull/11505))
 
 ### Deprecated
 
diff --git a/server/src/main/java/org/opensearch/search/aggregations/bucket/FilterRewriteHelper.java b/server/src/main/java/org/opensearch/search/aggregations/bucket/FilterRewriteHelper.java
index e34d9e480cdac..804f179a0990e 100644
--- a/server/src/main/java/org/opensearch/search/aggregations/bucket/FilterRewriteHelper.java
+++ b/server/src/main/java/org/opensearch/search/aggregations/bucket/FilterRewriteHelper.java
@@ -248,7 +248,7 @@ public static class ValueSourceContext {
          * @param missing   whether missing value/bucket is set
          * @param hasScript whether script is used
          * @param fieldType null if the field doesn't exist
-         * @param afterKey
+         * @param afterKey  for composite aggregation, the key of the last bucket in the previous response
          */
         public ValueSourceContext(boolean missing, boolean hasScript, MappedFieldType fieldType, long afterKey) {
             this.missing = missing;
diff --git a/server/src/main/java/org/opensearch/search/aggregations/bucket/composite/CompositeAggregator.java b/server/src/main/java/org/opensearch/search/aggregations/bucket/composite/CompositeAggregator.java
index 0fe61532a5de5..23e875645d344 100644
--- a/server/src/main/java/org/opensearch/search/aggregations/bucket/composite/CompositeAggregator.java
+++ b/server/src/main/java/org/opensearch/search/aggregations/bucket/composite/CompositeAggregator.java
@@ -602,7 +602,7 @@ public void collect(int doc, long bucket) throws IOException {
                 try {
                     long docCount = docCountProvider.getDocCount(doc);
                     if (queue.addIfCompetitive(indexSortPrefix, docCount)) {
-                        if (builder != null && lastDoc != doc) { // TODO reading how can lastDoc == doc?
+                        if (builder != null && lastDoc != doc) {
                             builder.add(doc);
                             lastDoc = doc;
                         }