Find and fix root cause of failures in Functional JavaScript Performance test(s)

Problem/Motivation

Every once in a while, random test failures occur in Functional JavaScript Performance test(s).

This issue is here to find the root cause on why the "normal" expected count of the various assertions can sometimes vary.

Steps to reproduce

Proposed resolution

Merge request link

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet