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Qtractor graphics becomes very slow with many items

Today I tried to write my first song in Qtractor today using MIDI and samples in the arrangement. At 145 BPM I used approximately 3 MIDI items and 15 audio items per bar. It played well on my fast desktop until I copy and pasted the song to 32 bars long, then it turns into a slideshow when I scroll the arrangement. During playback I only use 10% CPU, but when I try to scroll or zoom, one CPU core goes to 60% and stays there until scrolling finishes.

I think the problem may be the same as one of these.

rncbc's picture

and what zoom level?

take note that this "slowness" is somewhat expected on pretty high zoom levels. specially the horizontal one. it can be improved like with pixmap image caching, however not a top priority atm.


darkcity's picture


We have been discussing this problem here-

Maybe it would be possible to switch to simplified graphics for people who wants lots of tracks?

BTW the first and most recent link on 7bitaudio's post now has a digia URL-

rncbc's picture

may i look at a screenshot evidence, just to let me have an idea of how many clip item are in the scene?

otoh. do you sense any different behavior whether you switch qt_graphicssystem ? try launching qtractor with either of these:

qtractor -graphicssystem raster
qtractor -graphicssystem opengl


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