GUI interferes with host refresh rate/keyboard polling (FL Studio)

[bryc]

In FL Studio, whenever the GUI is active, the plugin causes the host's oscilloscope to update less frequently, and it also affects the playing of notes via keyboard. When I hide the GUI, the issue doesn't occur. See video:

fl.mp4

I've never encountered this before in any plugin. The only thing that fixes it is to explicitly bridge it (as a separate process).

[bryc]

I'm now noticing that this issue can be localized to the keyboard at the bottom of the GUI. If I hide it by dragging it off-screen (below taskbar), the lag disappears.