Slow library scrolling on OS X Mavericks

[RJ Skerry-Ryan]

Reported on the forums:
http://www.mixxx.org/forums/viewtopic.php?f=3&t=5677&p=20532&hilit=mavericks#p20532

I upgraded to Mavericks and can confirm.

I've reproduced with the attached minimal 1.12.x-style skin.

Simply comment the "background: white;" line in the style and scrolling performance returns to normal.

Potentially related QTBUGs:
https://bugreports.qt-project.org/browse/QTCREATORBUG-10491
https://bugreports.qt-project.org/browse/QTBUG-34546

[RJ Skerry-Ryan (rryan)]

Also, it seems to improve if you hide the BPM and Preview columns. Perhaps our delegates are acting up? Need to stare at some profiler output.

[Smashuu (smashuu)]

It's not just the library pane for me, the whole UI (waveforms, meters, etc.) hangs briefly at each step of library scrolling. Actual playback is not impacted, fortunately.

[RJ Skerry-Ryan (rryan)]

Blah, this still sucks. I can't figure it out.

Styles that seem to make the QTableView performance drop through the floor on Mavericks and up: border, background-color, alternating-background-color

[RJ Skerry-Ryan (rryan)]

Dug into the Qt code for CSS rules a bit -- setting background, alternate-background-color, and selection-color do nothing more than set a custom brush on the palette.

Rendering a table cell is nothing more than a fillRect using that custom brush.

Still extremely confused -- this would suggest all custom brushes introduce this slowdown -- which maybe suggests why our delegates also cause a slowdown.

[Owen Williams (ywwg)]

That sounds like a bug with QT -- have we tried asking them?

[Jess Boerner (jessboerner)]

Any updates on this? We really should be pushing this to the top, Mac is awesome for the audio latency. If we can get a snappy GUI to go with it people will have a reason to use our software over paid or other free alternatives.

[Owen Williams (ywwg)]

Is this still happening with recent beta builds? I don't have an OSX dev environment

[Foss-4 (foss-4)]

Testing the latest 1.12 beta from the website with OS X 10.10.5 Yosemite can not confirm any lagginess.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/7286