[nothanksmydude]

AFAIK, most modern game engines have a threshold of headroom for leftover time that must be hit to eliminate needless spin, but also stay responsive.

Back when everyone was targeting 60fps, >~2.25ms of 'leftover time' was needed during the individual 16.6667ms run of that loop to actually trigger sleep instead of spinning.

Note that's specific to the graphical rendering thread, and things like the mouse/kb input have their own sleep durations, with or without thresholds.