Yesterday night, I found something. My OS is win 98 (with Bryce 4, 1,4 ghz, 512 meg of RAM) While rendering, I usally open windows explorer and put Bryce on "background task" to prevent any hit on the keyboard to stop the render. It seams that rendertime is TWICE LONGER than Bryce in "front task" (excuse my english!!). Win98 seams to be really bad with multi task. Can you confirm it, is it the same with Win 2000?