Overall, responsiveness of 8 and 8.1 "feels" like Windows 7 - except when downloading a file in the background...
During a d/l the system becomes sluggish to clicks and very slow to open programs - may take :30 to one minute.
No difference whether the system is set for "programs" or "background" performance. Same thing since 8.0 beta.
Disc is not fragmented. Caches are clear. No error messages appear in event viewer.
Suggestions welcomed. Win 7, on the same 2600K/8Gb RAM machine, has never had the problem.