Add release note for GL #5022

diff --git a/doc/notes/notes-9.21.3.rst b/doc/notes/notes-9.21.3.rst
index d9e3d843e4c1dac66684186f5ba63d6435266781..bb0fb99a9a88bd8a4955f59e0e3811b33c4dc938 100644 (file)
--- a/doc/notes/notes-9.21.3.rst
+++ b/doc/notes/notes-9.21.3.rst
@@ -120,6 +120,9 @@ Feature Changes
   keys have become unavailable, this will prevent the internal key
   manager from running.
 
+- Reduce memory footprint by optimizing commonly-used data structures.
+  :gl:`#5022`
+
 Bug Fixes
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