I remember Byuu (RIP) wrote an article around ~10 years ago talking about why BSNES/Higan was "slow", explaining that it's really not slow given what it's trying to do. The more accurately you simulate the chips, there is simply more over overhead involved with synchronization and whatnot.

I remember in that article they mentioned a Pong circuit simulation like this that was getting something along the lines of 10FPS of gameplay, which astonished me. You don't get a lot simpler of a game than Pong and even on amazing hardware it was still unplayable if you want the truest form of emulation.