UI unusably laggy unless forced to use xwayland

Insync’s UI becomes unusably slow unless I force it to use X11/xwayland on my Wayland setup. When I say “unusably slow” i mean that each click takes almost a minute to register, and sometimes it seems to just freeze completely.

My system is:
up-to-date EndeavourOS
KDE Plasma 6.1.2
Ryzen 5800X
Nvidia RTX 3070 with the latest stable driver, which added proper Wayland support (555.58.02-1)
2560x1440 144 Hz monitor set to 125% DPI scaling

If I launch it with the --qt-qpa-platform=xcb launch argument, then it’s fine. But if I don’t, it’s completely unusable.

Let me forward this to our engineer to see what’s going on. Thank you for your patience, @danileon!