I realize this topic is a couple years old, but came up on search and figured I would reply instead of creating another one.
I do see the same issue, quite frequently, and have for a long years. I figured it was due to my macbook air being slowish and a little long in the tooth, but I recently got a new maxed out MBP and my total finder install suffers the same issue, despite far fewer things installed and much higher performance/ram. Almost every time I try to access TF after it's been in the background for a while (hours), or the computer has slept, something freezes up the UI thread and it takes 15-30 seconds for it to unstick itself (which it does most of the time, only very infrequently crashing).
Anyone have thoughts/ideas on how to improve this? It's not deal-breaking, but it's really bothersome. Happy to provide any info that may help narrow down causality.