Memory regression on searcher #6892

Describe the bug

Searcher memory usage increased significantly after upgrading between edge commits cc420c3 (Jul 25) and d18e34e (Oct 2), without any noticeable traffic pattern change.

Steps to reproduce

1. upgrade to the latest edge (with commit d18e34e)
2. observe that the searcher memory slowly increases

Expected behavior

Memory consumption should remain consistent with baseline levels observed on commit cc420c3.

Additional Context

See memory consumption graph on a single searcher; deployment happened on Oct 6 around midday, and was reverted on Oct 9:

On the same searcher instance, the cache usage increase a bit, but not noticeably:

Number of targeted root split and leaf split on this searcher: