@AgedLove Good idea! I played around with different settings (most of the time editing the config file directly over SSH) for vsync in combination with different setups for output and renderer. So far, I could not find a combination that has both (smooth videos and no crackles when mouse is moved). I think I'll stick with vsync turned off, as many games are unplayable otherwise because of the mouse issue.
This is also recommended in the Wiki (when using the pastebin link; the provided default config in /recalbox/share/system/configs/dosbox has vsync set to true instead).