It wants a remarkably high RSP/CPU interleave but that causes the driver speed to be halved, more or less.

Ah, such an awful position to be in. Definitely been there: choosing between playability on modern hardware, or correctness that nobody in the world can yet enjoy smirk

May I ask a rough estimate of the number of synchronizations between the two processors per second required to play Zelda 64 rev B, if you don't mind?