What is your operating system?
Linux Bazzite 44, flatpak. I’ve had this issue before on Win10 and Win11 in the past, but it has been some time since I ran Windows.
What is your Shotcut version (see Help > About Shotcut)?
26.4.30
Can you repeat the problem? If so, what are the steps?
- Create a project with a dozen or so video clips totaling at least an hour in length; the more video, the more pronounced this issue gets.
- Put the clips into the timeline and make 20 or so cuts, edits, filter effects etc. to each one. Use the Undo feature once per clip (this is to show how much slower it gets the longer the video is).
The result I am getting is that the longer a video is, the more video clips are included, and the total number of edits all seem to impact the Undo feature’s performance (as well as using simple keyframes; I can create a separate bug for that if desired). I’m currently editing a video that’s up to 45 minutes long, and it takes around 30 seconds for the Undo action to finish processing, even for extremely simple actions like moving a single clip or splitting a clip at the playhead. (For this reason, I tend to use the Rejoin With Next Clip option instead.)
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Hi kurazarrh,
I have had the same issue on Windows across multiple versions. I usually take 1-3 hours of video (all on a single track) and edit it down to 5-10 minutes. This results in possibly triple digit cuts along with multiple filters and increasing the speed of some clips. When first starting the edit, Undo is fairly responsive. However, the further I get into the edit, the longer it takes for Undo to work. I’ve never timed it but, in the worst scenarios, I would guess it could take 30-45 seconds to perform a single Undo operation. I put my voice-over audio on a separate track and Undo always works quickly on my audio track.
Since this has been an issue as long as I can remember, I just assumed it was something that couldn’t be fixed.
-Mike
I’m also doing this often and have noticed the same thing - when the timeline gets long and complex the undo operations that affect all clips (for example undo-ing a ripple trim) sometimes take 20-30s. In contrast, simple undo effects that only impact one clip are instant (like undo-ing a filter change).
The weird part I don’t really understand (because let’s face it, a long complex timeline makes sense to take a long time to undo) is that some filter UIs become laggy as well (the color grading one for example).
My way of dealing with the long undo on big timeline is to.. not use undo for clip movement actions. This sounds weird but hear me out: for example instead of undo-ing a trim, just drag the clip’s handle manually to whatever it was before. Instead of delete, I use cut (ctrl+x) so if I want it back I just paste it (ctrl+v). And also: disable ripple, use lift instead of delete and manually move clips if gaps appear, etc.
And in the end don’t forget that even big name paid editors get really laggy on long complex timelines.
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Hello there, same issue here. I had a posting about that some time ago Strg+Z takes ages - Bug - Shotcut Forum
Daniel taught me to separate big projects into smaller projects. Thanks for that @daniel47 . I normally separate 30-minute-episodes in around 7 to 10 sub-projects. In the end they are combined in a master project file (yes, shotcut can open an .mlt in a .mlt in a.mlt).
To be honest, since 26.04 i do - sorry - i maybe - do have the feeling, that Undo became less stable. There is no actual evidence. I just noted twice, that after some minutes CPU-melt of undoing my project was rubbish. Like 30% of clips were at the wrong place, without having the chance of undoing again. Best practice is to kill Shotcut and hope for autosaved progress. I recently train myself to ctrl+alt+s backup before Undo.
Still, Shotcut is incredibly awesome. As @alex007 said: Memory Leaks are something to deal with - so i do.
Correct, separating the edits into smaller projects is a good workaround (glad I could help you).
Weird, for me it’s the opposite, I’ve seen way less undo destruction in the newer releasesand every time it is in complex multi-track scenarios - it helps to report the bug if you can reproduce it consistently.
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Thanks for the tips! I already do some of them, but I didn’t even know that dragging the handle of a recently trimmed clip would automatically bring back the trimmed part. I thought trim = delete. 
I’ve never used any other big-name editors so please don’t get me wrong, I would never complain about Shotcut. I love Shotcut and the community which is why I never bothered bringing this issue up to the developers as a Bug. I just assumed it was something that couldn’t be fixed due to the complexity and length of my videos. I was just letting kurazarrh know that they’re not alone with this issue.
-Mike
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