Lag while clip skimming in the FCPX browser - Sonoma + FCP 10.6.10

You say "skimming" but in your screenshot it appears that skimming is turned OFF:

Are you really skimming or clicking and pressing space to play?

Please clarify.

Also: when the application is not behaving correctly, one the first things to try is to delete its preferences. To delete preferences, hold down command and option while starting FCP X and click Delete Preferences. The application will start in a default state, and open an "Untitled" library. Reopen the library you were working on, set the preferences the way you like them, and try again.

Any changes?

I have spent a lot of time researching this and hopefully will have some more info soon. Not a fix, just more detailed info that may help Apple pursue a fix.

This case is difficult because it involves things that are hard to measure, such as subtle differences in skimmer responsiveness in certain situations. These only happen for specific types of mouse gestures.

E.g, if you play a clip in the Browser in list mode, press the spacebar to halt the playback, then move the mouse pointer beyond the playback point in the clip, it can take 1-2 sec in some cases to start skimming. However, if the mouse pointer is in motion over the clip when pressing the space bar to stop playback, the skimmer will instantly become active -- on both 10.6.5 and 10.7.1 on MacOS Sonoma 14.5 on M1 Ultra.

Likewise if you stop playback, then just click at the desired point in the clip, the skimmer will also instantly become active -- on 10.6.5 and 10.7.1.

This only happens if you stop playback, *then* move the mouse pointer, don't click on the clip, and just wait for the skimmer to activate. In that case there is an apparent skimmer auto-activation difference between 10.6.5 and 10.7.1, at least on Sonoma 14.5 on Apple Silicon. It also may vary based on the exact codec and whether the clip has audio. I'm still testing that.

The XCode Instruments data currently seems to indicate it might be a real problem, since the thread that activates the skimmer encounters a semaphore timeout and gets blocked on some other resource for 1+ seconds. I can't yet tell what it's blocked on; it might be a GPU resource.

I have tested this on two macs - one Intel, one M1 Max - running Sonoma.

This appears to be something in 10.6.10. I tried 10.6.5 on the same macs, and it does not have the delay.

AFAICT, it's not Sonoma but 10.6.10 that has the problem.

The same is happening with the grey skimming icon. When 10.6.10 is launched, the icon is grey, even though skimming is on - as LocaAlicia pointed out. Again, 10.6.5 does NOT have the problem.

Sonoma 14.5 on M1 and Intel Macs, FCPX 10.7.1, can't replicate this. The first thing I'd question how much free space is on the system drive. Since we're expecting FCP 10.8 soon (hopefully by the end of the year) that will fix it, maybe? In the mean time, I'd recommend updating to the latest macOS and FCPX versions.

Thanks so much for this insight! Any further info you find would be great :)

To answer other people's points - I haven't updated to Sonoma 14.5 yet (as I don't like to update mid project) but don't see why it would fix the issue (especially given what joema said above). I'm on the latest version of FCP (10.7.1). It's not a disk space thing as I have 300GB free at least.

If I understood correctly from others' experiences, FCP 10.6.5 didn't have the issue - all of the others (certainly from 10.6.8) do have that bug.

For me, it happens in the Media Browser even when I'm in full clip view; when I play a clip, then pause and move the cursor to another clip (the red line takes 1-2s to catch up). It only happens if I was first playing a clip within the Browser, not if I'm just skimming around. Still really annoying when I'm in shot selection mode ;). Oh and the clips are just proxies of 4K files - no effects applied, not even a LUT.

I can intermittently replicate this on Sonoma 14.5 on my M1 Ultra on FCP 10.7.1. I just used a 1080p Quicktime color bars test clip from Apple, so it does not need a difficult codec or effects.IMO it’s pretty minor, but it shouldn’t do that. I got some traces using XCode Instruments and am studying them. I need to go back and try some older FCP versions.

The main FCP UI thread is getting bogged down for a sec or two in some cases when starting a skim operation in the Browser in filmstrip mode.. It’s doing lots of recursive calls to the MacOS Core Animation framework. I don’t know why. It’s a “fit and finish” thing, just a little irritating if you’re trying to work fast using the skimmer.

I’ll try to get some more info.

your screenshot it appears that skimming is turned OFF:

I think it's a bug from version 10.6.10, but when I start FCP, skimming is always ON, but the display is gray. It's a pain to have to press the S key several times to adjust before starting editing, so I'm looking forward to it being fixed soon.

There is no skimming delay on MacBook Pro2020, Ventura13.6, FCP10.6.10(Japanese version)

You can copy it using AirDrop or put it in a usb drive and bring it to the other mac.

I no longer have 10.6.8 (or rather I do but it is put away in an external drive, not readily at hand), so I cannot say if this particular issue was there or not. I kept 10.6.5 on my mac because it is the last that works on Big Sur and I need to share some libraries with an older mac that only goes up to that OS.

You can access feedback from the Final Cut Pro menu.

I'm experiencing this too on a Mac Studio with M1 Max - Sonoma 14.4.1, Final Cut Pro 10.7.1. Can't believe it's not fixed already...isn't everyone experiencing this? It only happens in the media browser, not on the timeline, as you said. It's incredibly annoying when I'm quickly skimming and selecting from a load of clips, as I can't get into any kind of rhythm, have to keep anticipating the lag!