FCP Runs Slow on iMac Pro

There might be some indications in the spindump that threads are hung on URL-based media references, such as media on a network or cloud-based resource. Do you have any media or libraries on any network or cloud-based location?

I have now examined the spindump extensively, and believe the problem might be the large number of synchronous I/O operations being performed to inspect assets and check proxy availability whenever switching between original/proxy media. The high thread count and GCD queue utilization indicates FCP is processing a complex task with many assets, maybe thousands of clips.

How many of your media files in all libraries on this machine have proxies? Are the proxies stored inside the library (the default) or did you define an external storage location (ie outside the library)? If so, what drive type are those on, and what drive type is the library itself on?

I have edited documentaries using a library containing 8,500 4k H.264 clips, all of which used proxies, and that was on an iMac Pro. It was a bit sluggish but I had no problems switching between proxies and regular media. The library was on the internal SSD and the media was on a 32TB OWC Thunderbolt 4-drive RAID-0 array. In this case I used the FCP Library Inspector to define a separate storage location for the proxies. I think I had those on another drive array.

Your Etrecheck report shows you have several kernel panics, the last of which was on 4-15-24. Do you remember the circumstances? Did the entire machine crash or spontaneously reboot?

[Edited by Moderator]

Just to set a benchmark here, I am running an iMac Pro with a very quiet Promise Pegasus3 R8, very fast, no issues. In fact, I'm surprised my M1 Pro Max MBP is not really much faster than the iMac Pro, except for exporting from FCPX, which is sort of kind of significantly faster, but not blazingly faster. 50% of my system drive is free space (it's only the system drive that needs the free space, secondary drives don't matter). So, there you go, I would think as stated this is an I/O issue.

Oh, I'll throw out there that too many external drives connected to a computer at one time can slow the whole system down a bit. Seen it over and over, lots and lots of small drives on one computer. Connect the one your using at that time, leave the others disconnected.

Yeah, the older and some smaller Promise RAIDs are a bit noisy when they get warm.

I think only by doing it off the forum

A possible workaround is to post a link to a youtube video - that is allowed.

You can put some other link in the description for the youtube video.

Do you have iCloud Drive enabled in the Mac's System Settings? If Desktop & Documents Folders is enabled, any media you store on the Desktop or in the Documents folder is in iCloud.