Performance and workflow issues in Kdenlive with large timelines, razor tool behavior, and timeline zoom

Help
1

I’m running into several workflow and performance problems in Kdenlive, and I’m trying to figure out whether this is expected, a known limitation, or something that I should report as a bug. I need advice on best practices, optimization, and whether there are workarounds.

Setup

Two video tracks, each ~1.5 hours long, synchronized with two corresponding audio tracks. I cut out the unwanted parts, so I end up with hundreds of individual clips on the timeline.

Problem 1: Severe lag when timeline contains many clips

After I accumulate about 800–1000 separate clips (after cutting), Kdenlive becomes extremely slow:

  • scrolling the timeline lags,

  • zooming the timeline lags,

  • playback + editing at the same time becomes almost unusable,

  • razor cuts take much longer,

  • UI interactions start freezing briefly.

This is not a hardware bottleneck. The system resources are barely used. The bottleneck seems to be inside Kdenlive itself. This is happening at the very first stage of editing before I even add effects or compositing. Working with this amount of material already becomes uncomfortable.

Problem 2: Timeline zoom steps are too coarse

The timeline zoom jumps in large steps. Compared to DaVinci Resolve, the zoom is not smooth. With the performance slowdown from problem #1, each zoom action becomes even worse — one zoom step turns into three because the timeline freezes before it finishes zooming. Navigation becomes very painful with many clips on the timeline.

This is not just a usability detail — it becomes a workflow blocker when the timeline is dense.

Problem 3: Razor tool behavior

I have 2 video + 2 audio tracks. When cutting, I want the razor to cut all four tracks at once at the playhead position.

Current behavior:

  • Razor cuts only the selected clip.

  • I have to make sure all four clips are selected.

  • That means: select clips → switch tool → cut → switch back → repeat.

Doing that hundreds or thousands of times during playback becomes slow and cumbersome, especially because of performance issues above.

If I select everything (Ctrl+A), Kdenlive tries to select all ~800 clips and freezes again.

What would help:

  • an option for the razor tool to cut all tracks at once at the playhead, regardless of selection,

  • or a global setting: cut active position on all enabled tracks.

Something like:
Cut → All tracks / Cut → Only selected clips.

Right now it feels very inefficient for real-time editing.

Questions

  1. Are these limitations known issues?

  2. Is there a recommended workflow for handling hundreds of clips?

  3. Is the slow performance a bug or an architectural limitation?

  4. Are there existing feature requests for:

    • smoother timeline zoom,

    • global razor cut mode,

    • better scaling with many clips,

    • timeline performance improvements?

  5. Should I open a bug/feature request in the tracker?

Summary

The problems are:

  • Kdenlive struggles with large numbers of clips on the timeline.

  • The timeline zoom isn’t smooth and becomes worse with large timelines.

  • Razor tool requires constant selection switching, which is slow and impractical.

I’d appreciate any guidance, workarounds, or confirmation that these areas are already planned for improvement.

2

Yep, is a known problem and investigation and work is ongoing. As a possible workaround, you may want to experiment with sequences to reduce the number of small clips and fragments in the (main) timeline.

Depending on the method you use for zooming it goes in increments of 1/21 or very smooth. Using Ctrl+MW (mouse wheel) or the - and + icons in the status bar (bottom right-hand corner) zooms in said increments; using the handles of the timeline horizontal scroll bar zooms in and out very smoothly.

Agreed. We should discuss this further here in the forum before you open a wish list item in the official bug tracker. Thanks.

And thanks for this comprehensive post with a lot of detail. This helps us identifying pain points (or confirm existing ones we already know about) in our continuous improvement efforts.

1 Like
3

“expected” probably isn’t the word I’d use, but yes as Bernd noted, this is a known issue that people with very large projects have seen before.

After I accumulate about 800–1000 separate clips

Are you also using lots of keyframes (for things like motion tracking where you might have hundreds or thousands of them in a sequence too, as opposed to 2 or 3 per clip)?

In the projects I’ve seen this with it seemed to be somewhat correlated to the number of keyframes more than the number of clips - but it takes really large projects to reproduce it, so it hasn’t been easy to quickly characterise in detail yet.

If you disable clip thumbnails it should help somewhat, even if you only disable the video ones if you need and use the audio waveform.

The bottleneck seems to be inside Kdenlive itself.

My first bet is on it being something ‘accidentally quadratic’ in the UI QML - either inherently or as a result of something we are doing with it - but probably some of both.
There have been a lot of improvements to resource usage in the last few years - but this issue only seems to hit the largest projects, and it has the character of getting exponentially worse with each addition to the project after you hit the point where it begins to be noticable.

It does seem to be related to the size of the current sequence as well as the size of the project, so if you can split your editing up into smaller sequences that you later combine, that should help somewhat too.

But really it needs someone with a project that can reproduce it to actually profile it and see where the real bottlenecks are, which is on a few todo lists, including mine, but hasn’t actually made it to the top of them just yet. I personally have a few projects that are bouncing off this limit, so fixing it is Definitely Interesting once it gets past the things that are still more immediately urgent.

When cutting, I want the razor to cut all four tracks at once at the playhead position.

We could call it Ctrl+Shift+R - if you haven’t reassigned that to some other operation : ) That cuts all the tracks you haven’t locked. And you can assign it to a different key if you have one you’d prefer.

4

Thank you for the advice! I’ll try sequence workarounds in my next projects.

Yeah that’s true but when the sequence is loaded with 800+ clips, zooming with the handles is even more laggy then with the mouse wheel… I’m using trackpad by the way.

I’m not using any keyframes or animation in my particular case. I simply have two video files, each 1.5 hours long, and I cut them into many pieces.

Wow, I didn’t know about that feature! It would be handy to be able to do the same with the Razor Tool as well: cut all the clips right at the mouse position while the playback is ongoing.

5

Talking about the timeline zoom, I wish it could be implemented just as smoothly as it is in Blender. They did a great job with it.

6

Ok, that’s an interesting data point, and definitely makes it easier to create a reproducer for testing - my projects where I’ve hit this are hundreds of raw clips, on the order of terabytes in size - so they are unsurprisingly somewhat unruly in most dimensions. and we don’t see that many reports of this, so it is a known problem, but we don’t really know what a minimal reproducer looks like yet.

Is there any chance you are willing and able to share this project for testing? If you can archive it with all its resources and make that available, that makes it lower hanging fruit for someone to be able to run more tests. We might have to see how large that archive actually is and if there are limits to what we can attach to bugzilla, but if we can get a bug report open with a minimal reproducer that would be a good step toward getting more work on this done.

Though in theory, if that’s really all it takes, we should be able to reproduce it with one relatively short clip, placed many many times in the timeline - if someone has time to whip something like that up?

It would be handy to be able to do the same with the Razor Tool as well

I think you’ll find that once you get some of the keyboard shortcuts into muscle memory, using them in conjunction with the mouse makes for a much nicer editing experience than lots of tool switching of the mouse itself. Once you’re familiar with the basics of how kdenlive works, it’s well worth browsing the list of them (and the options that are possible but don’t have a key bound to them by default), just to get a sense of what is possible, and either useful to you today or when you have some task to do in the future. The ones you use a lot you’ll remember pretty quickly.

Things like Resize Item Start - ( and end - ) will do common tasks that take much mouse manipulation in a single keypress.

I’ll try sequence workarounds in my next projects

If you’re still needing to do more work on this one, you could also look at “copy selection to sequence” - which will let you select a block of clips (I’d use the lasso selection to make sure you get everything), and have them moved to a separate sequence with that sequence then nested in their original place.

There’s no guarantee it will help in your case, and I’d definitely make a backup copy of your project before you start trying that in case something goes Horribly Wrong - but knowing if it does help your case will be another interesting data point and might help you finish it less painfully.

7

I think the Multicam-Tool can help here. I’m not sure about the audio cut.

For re-cap: you have two 1.5h long A/V clips (video and audio. I guess is coming from OBS) which you put into the timeline. Question:

  • how many audio channels does the audio have? Like: 2 channels for stereo only?
  • What is the clip resolution and container (HD, 4K / mp4, MKV)?
  • If you switch off the video and/or audio thumbnails in the status bar. Is Kdenlive more responsive?
  • What are your OS and hardware settings (Windows/Linux, 32GB RAM)?
  • Do you have problems with rendering the final 1.5h video (like Kdenlive crashes)?
9

Okay, I’ll do it with my next project. I assume it would have the same amount of clips cuts. I’ll share soon.

Yeah, you hit the bull’s eye.

Two audio tracks, both stereo

HD, mp4

Yeah, the cut operation seems like became more responsive with the video thumbnails turned off. But the zoom/scroll timeline I found is still struggles.

Ubuntu 24.04, 16GB RAM

No I don’t have any issues with the rendering

10

Can anyone give me their email so I can grant access to the file on google drive?

11

Are you able to open a report and attach it to that in the bug tracker
https://bugs.kde.org/enter_bug.cgi?product=kdenlive ?

12

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There is no option in the bug reporting form for the version I use.

13

Because that’s either a nightly build or the RC. Just state it in the bug report text.

14

Alright, I’ve opened a bug report with my project attached :slight_smile: