Found a Solution that Works for Me..
Change the compatibility settings to "WINDOWS7"
I too have had an issue with Nitropdf pro hanging from 5 seconds to 20 or so seconds, for a long time.
appeared to overwhelm the Disk drive causing it to be at 100% usage. Also will hang up the Screen.
nothing will respond.
This has been the case even with versions 10.x. and Now versions 11.x I have done everything suggested, but nothing seemed to work.
deleting temp files, using the cleanup program, reinstalling.
But Good News... Today, I decided to Change the compatibility settings to WINDOWS7
This actually appears to have stopped all the hanging every few minutes.
Even with Huge files, and Small files.
My OS is Windows 7 SP1
My Current Nitro version 11.0.7.425
band