Moving masks becomes unusably slow

Latest shotcut windows 10 6600k 16gb 1060 6gb

proxy and output scaling on @ 360p ( side question, why does output scale need to be on if I’m already using 360p proxies? )
Started editing clip manually tracking moving mask to add keyframes. Started OK, now it is becoming extremely slow.

saved / closed restarted. Same issue. Tried moving files locally, did not help. ( projects across LAN on otherwise unused 1GBE )

Shotcut is using 435mb of RAM. CPU usage doesn’t go over 50%. task manager is showing all cores so it’s not spinning on a core or anything.

The hell is going on?

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As an experiment, it would be great if you could move the files to a local SSD on the editing machine and then compare the performance. I think a lot of people on this forum would be interested to know if you see a difference.

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that was actually the first thing I tried, it did not seem to make any difference

I suspect the issue is with a large number of keyframes?

just dragging mask all over quickly makes computer choppy and uses ~60% on all CPU cores


working on 2nd of 2 masks. tried clearing keyframes, still unusably slow.

tried working on first filter … it’s a lot faster. but it lags a lot when manually tracking mask around the shot while playing

ok, even the first filter is slow too after awhile.

deleting filters and re-adding them things become usable again.

so is it an issue of having many keyframes?

This is the sad experience of many of us. As soon as the elements of the timeline exceed a certain number (this quantity remains to be evaluated) well shocut suffers from an overall slowdown.
What would be interesting is to know the size of the MLT file and the number of lines in the file and the number of shotcut elements.
I don’t know if the element type or just the number has an influence on performance.
For me to date, I would say that 45min of timeline, 500 elements would be a maximum… (depending on the work and action that I do, it would be time to compare with other work…)

Several posts talk about it recently.

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