Cursor updates too slowly on Flatpak install

[Cuperino]

Pixelorama version: 0.10.1 from FlatHub

OS/device including version: Linux, KDE neon Testing Edition 20.04 running a KDE Plasma 5.25.3 X11 session

Issue description: Cursor updates slowly, lagging behind the system's cursor position by up to several seconds, resulting in rapid flicker between system cursor and app cursor.

Steps to reproduce:

1. Launch program installed from Flathub on system running KDE Plasma.
2. Hover cursor over user interface for a few seconds.

Notes

• Issue is specific to Flatpak. It doesn't occur when using the Snap package on the same system.
• CPU: Intel i3-7100U (4) @ 2.400GHz
• Intel HD Graphics 620

[Vilzuz]

Same thing its like trying draw with 2fps.