Window manager lags while application runs

[HalfVoxel]

I'm trying out the examples for rendy and I've come across an interesting issue that seems to happen for all examples. The application itself seems to run at 60 fps as expected, however when I try to move the window it moves in a very laggy way. Perhaps at 5 fps.
I also tried to move other windows and they move smoothly as long as they are not overlapping the rendy window. If the windows overlap (even just their shadows) then the movement starts to lag.

This seems to indicate that there's some synchronization with the window manager that is causing this. My first thought was that window events were not polled often enough, but since they seem to be polled at 60 fps I don't think it is that.

I'm running this on Ubuntu 18.04.2 using an i7-4790K CPU and a GTX 970 graphics card.

Does anyone else see this?

[HalfVoxel]

As a side note, this does not seem to happen on macOS with Metal.

[zakarumych]

This could be caused by event polling loop entering different state when you move or resize it.
Try confirm that loop indeed cycles at 60fps when you're moving the window.

[malobre]

I am able to reproduce on Arch Linux (Kernel v5.2.10), i3-5010U (iGpu) on wayland but only when running the quads example.
The animation is very smooth but the cursor (and window manager) becomes very laggy as long as the window is shown.
This happens even without moving or resizing the window.

This doesn't seems to happens when running the other examples (like meshes)