You can set the timestep for a collectionproxy to match any update frequency you like (e.g. slow-mo or fast-forward), but the collection’s update function will still only be called in sync with the rest of the engine.
The update frequency in game.project is capped at 60. Here is a more detailed explanation of how update frequency, variable dt, swap interval and gpu drivers play together: Variable dt causes game to run twice as fast (DEF-3146) (SOLVED)