Maya GPU rendering - "Clearing geometry" quite slow...

[hermit.crab]

Same as SonyBoy. I rarely post here but this problem is driving me absolutely insane. I have to remember to press Esc just before a render finishes in VFB or another 30mins' waiting ensues.
I'm not on a slow machine. Threadripper 3990x 256GB, RTX3090, super fast 4TB SSDs directly on the motherboard. Maya 2023, Vray 6.20.24.
This is a recent problem I've noticed in the past couple months. Large renders are a disaster (just doing a 16kspherical right now, 2hours to render and now going on 2 hours "clearing geometry" (writing files). It always eventually finishes but also happens on far smaller renders, 2ksquare I've waited a good 30mins before I can use my machine again. Small scene, nothing complex, no displacements. Do NOT even attempt to tick that LightMix pass.
I'm in the middle of a high pressure 18hr/day project and can't take the time and risk to start rolling back and running tests. It's not scene specific. I've dug out old projects that used to finish in a flash and now waiting forever. Any update on this would be extremely appreciated. This is the only mention I've found anywhere online.

Please, send the scene so we can troubleshoot. Also, this thread by stezza seems similar. Mind if you include answers to the questions I've asked him?