FCPX No longer updating thumbnails in real time in version 10.6.10 on Sonoma

As Tom said, FCP per se does not update the thumbnails during playback.

Maybe you had installed the free utility CommandPost, which has the ability to tweak some hidden preferences and make FCP update thumbnails and waveforms during playback.

You may want to try installing CommandPost and seeing if that is what you were used to.

It’s actually always been like that. Everything else in the application stops to maximize performance for realtime playback with multiple streams and effects.

Tom is right, I run a maxed out iMac Pro, latest versions of everything, it's always been like that.

THAT SAID; Sonoma and FCPX do have some lag and bugs I've been noticing are unique to this update combo. So it may be worse on your system due to that. I'd not write off "it always did that" because latest FCPX and Sonoma have some issues. I see it on 5 different Macs daily.

Oh yes, its control option then up down arrow, I have this project set to just show audio wave forms because the thumbnail re-draw is WAY too slow and not needed for the edit at all.

In testing, and out of curiosity, I toggled Show Reference Waveforms to see if that made any difference in audio waveform re-draw but it didn't seem to. I even dumped the audio waveform cache itself just for laughs but it didn't make a difference.

This project is on an NVME so speed isn't an issue, albeit they are 2-3 hour long projects (using several multicam angles) but the long single multicam clip I'm using (and only using one audio source) is just so slow re-drawing the waveform. Sometimes I just have to wait. I have noticed that FCP seems to remember audio waveforms at different zoom levels, like if I don't' see the waveform, then zoom out or in further it'll just pop in.

I half suspect it's how I edit, zooming in and out (command - and command +) a lot and swiping left and right on the magic mouse a great deal to move around the timeline; it feels like FCP is constantly re-drawing the audio waveforms. It really gives me the sense that something it's optimized within FCP regarding audio waveforms.

You don't need to have them. Just change the way the clips are displayed on the timeline. Click this button and choose the option you want.

It feels like an area that Apple could make more efficient though. I'm working on projects that are 2-3hrs long recently, and I don't need the thumbnails at all since it's mainly cleaning up the audio (lots and lots of talking) and I've' noticed that in longer projects like this FCP takes sometimes oddly long times to re-draw the audio waveforms, which I need to edit this particular project. It does feel a little buggy in how long it takes to re-draw them at times.

Not while you’re playing back.