diff --git a/release-notes/3.11.3.md b/release-notes/3.11.3.md
index e9c4debf6c..4f2577f0e6 100644
--- a/release-notes/3.11.3.md
+++ b/release-notes/3.11.3.md
@@ -82,6 +82,11 @@ Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://
 
     GitHub issue: [#6020](https://github.com/rabbitmq/rabbitmq-server/issues/6020)
 
+  * `rabbitmq-diagnostics memory_breakdown` now returns results much faster in environments with a large number
+    of quorum queues (say, tens or hundreds of thousands).
+
+    GitHub issue: [#6390](https://github.com/rabbitmq/rabbitmq-server/pull/6390)
+
 
 ### Stream Plugin