Thank you Y_Phil. Now we are getting somewhere.

a 512 bucket gets me 122 sec instead of 152. And rendering a 1080 x 1024 pix lowers it to 36 secs.

I use SSD and MVme for all my 3D work, then do backups on HDD. I find my MVme drives get too hot for two reasons. They sit under video card and if you flog them with compiling a game file, the temps reach over 65C, even with the heatsink on top. I never really thought that the EVGA RTX 3090 would generate so much heat. 420W does not seem like much when you read about it, but when the heat blows in your face ( I should put the computer on the floor), it is annoying. Sometimes I long for my 1080 ti. I mainly got the 3090, now that they prices are not sky high anymore, just for the amount of Vram. I have some scenes with 6 or more avatars, and all that sucks up a lot of Vram during rendering.