What does slowness mean to you? It is very subjective...
Capture a series of thread dumps while things are 'slow' and use that as a starting point to better understand WHY it's slow. [1]
- could be a product issue
- could be an index issue -- eg a corruption, or perhaps heavy usage of apache tika that's performing full-text extraction on some large number of assets in some remote datastore
- could be an implementation issue
From there we can better guide you .. but it could be anything without knowing more specific information.
[1] -- https://github.com/cqsupport/jstackSeries.sh