Most of the time when I'm working on peoples slow computers it's spyware, Malwarebytes is by far the best and easiest spyware cleaner out there. Check your hard drive space, if your computer is full of crap it will run sluggish. I only mention this because your a torrent user and probably have a crap load of stuff downloaded. Try to get rid of Programs, Games and or Movies you have that you rarely or never use. I don't think it's a virus because they usually render windows inoperable, but it doesn't hurt to run a scan. Make sure your only have one virus scanner installed on your computer. If you have more than one they will fight for superiority, which will slow your computer down or end up screwing it up "blue screens = BOSD". Your last step is to clean your windows registry, it probably needs cleaned up, .Good Registry Cleaner will improve your computer and Internet performance dramatically! Do all these and Perform speed here scanmyspeed.com once it will sounds better ...