[Jeff Feazell]

Hello Tom and anyone else who may be experiencing this issue. This reply is a little late, but this is the only thread I could find where this exact problem was described, so hopefully this solution will help someone.

I had this exact same problem. It only happened on one particular timeline, so I started removing individual clips to troubleshoot.

Sure enough, there was one particular (merged) clip that, when on the timeline, whether it was the video or audio, caused all these performance issues, pretty much making it impossible to work.

The interesting part is that the clip was identical in specs to all the other clips I was working with. It was just one particular take of one particular shot from the same camera as everything else, so I have no idea why it caused this.

This was a merged clip (meaning Premiere had created it from separate audio and video clips I had synced manually on a timeline).

I needed the footage, so I went back to the timeline I had used to sync all the audio and video, highlighted the source clips, and merged them again, just like before, created a new merged clip.

With the new one (despite being identical to the old one), the problem doesn’t occur. Worked for me.

If you’re working with raw source footage that didn’t need to be merged, try re-importing the clip into your project.