I also had at least 15-20 crashes a day with v9. I had my autosave set on 5 min and IR crashed for many reasons I recognize above.
But I can honestly say that I (3990X-256GB-win10-R25) and my colleague (3970X-128GB-win10-R25) experience significant improvement with the hotfix v9.1 !
I can now use the interactive renderer without crashing while renaming, splitting geometry off, duplicating instances and instanced lights, modifying geometry in polygon/point mode for instanced elements, fastly swapping cameras in the stage object, stop IR....
Sometimes I even think to myself 'oh, I should not have done that, it will surely crash now', but no, very stable again for long periods...
What a relief ! I hope everyone has the same experience now?!
thanks guys!