Preview performance issue since updating to v20.09

Windows 10
64-bit 26.0.2
Ryzen 5 3600, 32GB RAM, all videos and project stored on internal SSDs

Since upgrading to the latest version, I’ve been experiencing major performance issues when the playhead gets to the rhs edge of the screen and the software starts to auto-scroll the timeline as it continues to play.

When play from anywhere within the viewable timeline it’s great, but as soon as the playhead hits the end of the screen the system lags severely.

I can usually just about hit pause during the slowdown and it takes the system a while to respond and stop. Sometimes I can’t stop it and it will just keep going until Shotcut crashes completely.

1 Like

This sounds a lot like the issue that was first reported on here:

then later another user reported here:

As you can see in the discussion of the first link, this issue was addressed for the release of the latest version which is due to be published at any time now.

Can you please test last night’s build instead of the new release?

Besides the horizontal scrolling problem, you may also be experiencing a problem with memory usage. In addition to the scrolling improvement, this build has a change to reduce the amount of media files held open. Previously, it could be affected by systems with higher number (>4) of CPU threads.

Hi there, just tried it and no improvement I’m afraid (if anything, it seemed worse).

You’re right about memory usage - as the video played past the end of the timeline, RAM usage steadily increased until it consumed the 32GB and I managed to kill the process.

Memory usage seems to be a steady 3.3GB until the playhead hits the end of the window. Everything works great until I forget about the bug and let the playhead run on too far.

Unfortunately, I can’t remember when I installed the previous version of Shotcut, but I think it was an August release. That version didn’t have any issues for me.

I am unable to reproduce this. Is the problem specific to a project? Can you reproduce it in a new project, and if so what are the steps? Maybe it is something special you have at the end of a certain project.
Does it depend on some Setting such as Realtime turned off or the hidden GPU Effects? Maybe Display Method makes a difference.

Tried downloading 2020-07-11 release again and it works perfectly (same project). No lag, no RAM usage ramping up.

Back in the latest release, I tried turning off realtime, turned preview scaling to 360p, switched display method with no joy.

Where are the GPU effects? Are they in newer releases?

No. They used to exist but were made hidden 2 years ago. He was just asking in case you had them activated but since you don’t it isn’t a factor.

You did not answer all of my questions.

I really appreciate your 1:1 support, but I could only dedicate so much time to testing last night (UK time). Every time a test fails it can result in me having to hard reset the PC as Windows often stops responding before I can kill the process.

I don’t think there’s anything special in the project - it’s just a string of basic video clips of me talking over some slides. The few effects are fade in/out and volume gain. I’ll create a new project as soon as I get a chance.

I believe your problem is the same as reported here, which I have reproduced and fixed:

A workaround is turn off video thumbnails in the Timeline menu.

Here is the latest nightly with that fix to test

Yes I get these things too, whenever I play my video in the preview window it plays in very low fps, it makes it hard to see if you have done something properly
Even a well known YouTuber with a 2000 dollar pc was having these issues

This topic was automatically closed 182 days after the last reply. New replies are no longer allowed.