Yep – me too. I am getting a lot of beach balling since 10.1 and i have been trying to isolate the issue so I turned on the stop and warn when frames were dropped. I thought it was Multicam or synched clips that were the issue but was surprised this morning to see that frames were being regularly dropped with audio only clips.
I thought I’d take my thunderbolt raid out of the equation and moved the library to the internal SSD. Same issue. The files are .wav