a rather poor idea - esp. the frame part, mouse movement is not related to the display frame (rate). The latter can be rather high, e.g. 240Hz which is 8ms. Having a set delay and be in the boundaries (and not leaving it) is a significantly easier solution and easier to test too.

Overall the delay in tooltips (and configurable) has been a feature since the 90s (could set the delay in millis in some UI frameworks)

Tooltips pop up in many cases where there's no more being used. Tabbing through items, for example.