I'm working on a very simple, low res, pong clone and you can see a sort of motion blur effect that tires the eyes after a while, I think is due to the low frame rate (or maybe too high?).
This is due to display ghosting and cannot be fixed on your end (except by using a more reactive display). See the TestUFO ghosting test for an example.
To answer your original question, you can set a FPS limit by setting Debug → Settings → Fps → force_fps to a value above 0 in the Project Settings. However, it is not going to have any effect on display ghosting since it's purely an hardware issue.