Details
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Bug
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Resolution: Fixed
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P2: Important
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None
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5.12.4
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None
Description
I was investigating some performance issues when using Qt applications with QWayland on Gnome. The performance was much better when I turned off decorations so I started digging and it turns out that even just moving with mouse inside the application (not resizing or moving with the window) causes enormous number of QWaylandShmBackingStore::resize() calls, which shouldn't be needed in my opinion.
When I tried to run the resize() method only when the geometry changed, adding mResizeDirty property and changing it just when the geometry changes and then call the resize() method, the performance was significantly better, but there were unfortunately some glitches as my quick fix doesn't probably consider all possible cases.