* I'm running it on an IMac (Retina 5K, 27-inch, 2017)
* OS is Sierra 10.12.6 (fully updated)
* I have 16 GB of RAM
* Using an OWC external hard drive for storage
* Used same set-up last year editing a documentary, no such issues.
The only difference I'm aware of is that, with this year's project, I drag and dropped the clips from the external drive into the FCPX browser due to a pixellation issue with some of the clips when brought in via the Import function in FCPX.
The slowness is apparent in pretty much everything...razor cuts, shifting the timeline back and forth, playback, etc.
Thanks in advance for any help,