diff --git a/fe/fe-core/src/main/java/org/apache/doris/cloud/catalog/CloudTabletRebalancer.java b/fe/fe-core/src/main/java/org/apache/doris/cloud/catalog/CloudTabletRebalancer.java
index 69df53fcda94e1..2f0f323e64bcf8 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/cloud/catalog/CloudTabletRebalancer.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/cloud/catalog/CloudTabletRebalancer.java
@@ -517,14 +517,18 @@ protected void runAfterCatalogReady() {
             return;
         }
 
-        statRouteInfo();
-        migrateTabletsForSmoothUpgrade();
-        statRouteInfo();
+        try {
+            statRouteInfo();
+            migrateTabletsForSmoothUpgrade();
+            statRouteInfo();
 
-        indexBalanced = true;
-        tableBalanced = true;
+            indexBalanced = true;
+            tableBalanced = true;
 
-        performBalancing();
+            performBalancing();
+        } finally {
+            releaseSchedulingIndexes();
+        }
 
         checkDecommissionState(clusterToBes);
         inited = true;
@@ -640,6 +644,15 @@ private void performBalancing() {
         }
     }
 
+    private void releaseSchedulingIndexes() {
+        // These indexes are no longer used after balancing. Replace their top-level maps instead of clearing
+        // every entry so the complete tablet membership graphs can become collectible without an O(N) traversal.
+        partitionToTablets = new ConcurrentHashMap<>();
+        futurePartitionToTablets = new ConcurrentHashMap<>();
+        beToTabletsInTable = new ConcurrentHashMap<>();
+        futureBeToTabletsInTable = new ConcurrentHashMap<>();
+    }
+
     private boolean balanceAllPartitionsByPhase(ActiveSchedulePhase phase) {
         // Reuse existing "balanced" flags as a per-phase signal.
         indexBalanced = true;