Operating system: OSX
Graphics card: Radeon Pro 580 8192 MB
Short description of error
After a while of drawing (30 minutes to 1 hour usually) drawing with grease pencil becomes very laggy, too much so to be unuseable. Responsiveness seems to degrade suddenly when it happens, not gradually. This has been an issue for as long as I've been using 2.8 (various versions).
I have other apps open and switch windows occasionally. It could be that lagginess begins after switching away from blender and back to it again, but not certain about that. I haven't noticed the lag beginning *while* drawing. It seems to begin when I go back to drawing after some other operation (either within blender or in another app).
Exact steps for others to reproduce the error
Can't reproduce it reliably. Intermittent.