Purebasic uses XWayland in that case.
It seems the autocomplete window steals focus from the coding area.
A video can be seen here.
CTL+Z is hold down at 20 seconds. Ctrl+Y seems to be much less affected, but sometimes it is.
- This slowdown does not appear under an X11 session.
- When setting animation speed to "instant" in the KDE settings the autocomplete window can no longer be seen popping up, but the slowdown is still present.
- When focus stealing prevention is set to extreme in KDE Settings slowdown does not occur, but autocomplete also does not work (Autocomplete key is inserted into source code instead)
- GTK3 and GTK2 are affected.
- Also happens with an old version of PureBasic (5.42 tested)