I noticed this with my current project.... In the preview window, the proxy acceleration works perfectly. However, in the project monitor, it's a different matter. The proxies that are on the timeline were dragged out from the project bin, except for clip 3, which was dragged out from the clip monitor. The other clips, when played in the project monitor display the lower resolution of the proxy clip, but the performance is as if there was no proxy at all. This is quite noticeable on 4k footage and a proxy of 360p.... It plays back at about 1fps on my machine. Reproducible: Sometimes Steps to Reproduce: 1. Enable proxies for a project 2. Drag a bunch of clips on to the timeline 3. PLay back in project manager, drag around the cursor to get a feel for how slow the vida acces for video that used to be lightning quick. Actual Results: Video playback and seeking is slow from the timeline/project monitor, but not from the clip monitor. Expected Results: Performance associated with proxies. I'll attach my savefile.
Created attachment 99690 [details] Project file with the issue The third clip on this timeline plays back normally, the rest all show the proxy clip, but "feels" like there is no acceleration. Also, when having two video clips on the timeline, with one below another, the playback speed halves for the time that the clips overlaps, which is also something that never used to happen.
Oh, somehow I forgot to post my comment on this issue. I think the bad performance you are experiencing in timeline is caused by the track's composite transition, which are causing a huge performance issue. Can you try disabling them to see if it changes something ? Looking at your project file, it looks like only proxies are used in timeline.
Disabled the composite, ( after some looking ) and speed is now much better. However, there is still something special about those first two clips on the timeline. They still play as if there is no proxy, ie: slow. I'll make a clip to show you what I mean... When I try to reload the source clips for those two on the timeline, it hangs up kdenlive so badly that the window exit does not work, and pkill kdenlive works, but then on the subsequent load of kdenlive it just hangs... I literally have to shut down the virtual machine it's running on and unplug the disk, then plug it back in to make it work....
Created attachment 99699 [details] Just watch the playback speed for the first two clips The two clips seriously mess with the performance, it's almost as if the proxy is not activated, however, it is, as the resolution for them is pretty low. This may be a one-off, I'll create a few new projects and see if I get the same error, but definitely the project attached here is borked.
Ok, the slowdown is caused by the frei0r levels effect (added as a custom 70D in your project). Filters are processed on the project's frame size - in that case 4k, which is why you get such slowdown. As a workaround you can disable timeline effects when doing the editing and re-enable only when needed. "Timeline > Disable timeline effects" allows you to easily enable/disable all timeline effects.