I am unfamiliar with low-level workings like this, so forgive me if I'm talking out of my ass, but received wisdom from places like KVR Audio suggests that on modern machines, fixed point decimal math tends to be slower than just using floats because the integer registers are already clogged with routine operations like incrementing loops, etc. But some claim that anything that needs a phase accumulator as a wavetable index, like FM, still benefits from being kept as integers due to the expense of converting a floating point accumulator to an int address. FM doesn't have much arithmetic relative to its reads.

I wonder how true this still is. I've been having fun simply assuming it is, and these teardown articles and the other HN discussions around them have been very helpful.