In those JS tests where we do not restart the cluster (for performance - run time - reasons) the memory usage is kept increasing during the whole test.

This is most probably because of the combination of --storageEngineCacheSizeGB (the wireTiger cache size, in the tests 1GB) and the minSnapshotHistoryWindowInSeconds (the wireTiger snapshot history time, default 300 sec).

The idea is that reducing the snapshot time should keep the memory consumption lower.
Let's find a combination where the tests are green and the memory decreases in order to be able to reduce the necessary image size on EVG (and save a bunch of money)