Can confirm CPU part. I once tried to replace a 2d stepwise linear function interpolations (basically, a loop finding the right step, then linear interpolation, on a double; the function's objective is to rescale inputs before they become regression's arguments) by LUTs.
All of this looping was happening in another tight loop, and there were multiple LUTs.
It was a failure with overall decreased performance and increased cache misses. Plus, I could never get the same precision.
I went through 2 PCVR headsets and I'd never think: oh this is going to be mainstream (in the present state!).
Those headsets are not comfortable (sweaty); the hardware needed for anything realistic is top tiers; it takes PhD/time to configure (and goes out of sync!); the software ecosystem was(is?) not super stable; the interaction (controllers, tracking) is sometimes awkward (controllers are big, interfere with keyboard and real world). Often it small things like comfortable physical head position vs. position in VR world are not "lined up"
We'd laugh that it takes as much time to get into the VR plane simulator as to drive to the airport to fly real plane!
Compare a VR kit to a monitor pair, or a game controller (imo VR is kind of a cross of the 2) - both are mostly plug an play.
All of this looping was happening in another tight loop, and there were multiple LUTs.
It was a failure with overall decreased performance and increased cache misses. Plus, I could never get the same precision.