[Libreoffice-bugs] [Bug 113104] MacOS: CPU utilization while scrolling through a plain text document is around 90% on Retina HiDPI screens

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=113104

--- Comment #26 from Michael Meeks <michael.meeks at collabora.com> ---
Telesto - thanks for the profile - is there any more to the profile ? I'd love
to see lower down - and also where the other 50% of the CPU goes (only half of
it goes down that path).

It -looks- as if we're trying to do a synchronous screen update via some
ancient code-path, when we should really do an idle refresh - outside of the
event processing, so that we can skip frames if we can't keep up rather than
re-rendering on each one. I suspect there is a 2x from rendering each frame
twice there too.

Anyone else willing to run the instrumentation & look into the profile a bit
more - much appreciated. I would suggest that DrawAfterScroll is just bogus:

source/ui/view/gridwin3.cxx:void ScGridWindow::DrawAfterScroll()
source/ui/view/gridwin3.cxx-{
source/ui/view/gridwin3.cxx-    PaintImmediately(); // always, so the behaviour
with and without DrawingLayer is the same
source/ui/view/gridwin3.cxx-

Looks very dodgy to me - if you're compiling; no-op. that method, or just call
Window::Invalidate() instead on Mac and see if it fixes it.

Would love to know where the other 50% is though =)

Thanks !

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