Seems to be more pronounced when the patch is performance demanding.
From my original patch (which I can’t share), running in 2021.0.4-0321:
Similar behaviour (not as severe) can be observed when opening for example the Instanced Spheres patch from the help browser and increasing the spreadcount (eg. to 6000). The patch is running at stable 60 FPS on my machine, but as soon as I hover an IO-Box or inputs/outputs the framerate starts fluctuating.
Tested with 2021.4.0-0351