I'm also still getting some really poor performance on the Contacts database when trying to use open-ended filters (consistent search failed for text or numerical entry, not for single/multi select) - this is becoming quite a snag if I want to look up a user by a name I've kept in a field.
Oddly, it works if I apply some other filters. This feels similar to how magic searches fail a lot if I don't apply some other filters first, almost as if it's too big of an ask for the search engine