You aren't the first person to encounter this, but I was never able to track down the source of the problem. (I'm guessing you're using LDView as LPub's renderer; if you're using POV-Ray, then that would indeed be slow.) On some systems, LDView takes a long time to exit once it's done creating the image; I couldn't figure out why, and it didn't do this on my Win 7 computer.
You might try temporarily disabling User Account Control (UAC) to see if it solves the problem. I'm not promoting this as a solution, but if it does solve the problem, it would at least tell me where to look. Having said that, LDView shouldn't do anything that requires admin privileges.
You might try temporarily disabling User Account Control (UAC) to see if it solves the problem. I'm not promoting this as a solution, but if it does solve the problem, it would at least tell me where to look. Having said that, LDView shouldn't do anything that requires admin privileges.