I have a program from AVG that's a 1-click maintenance program. Once in awhile, my computer will start dragging just like you describe when online. That program also cleans up your browser. It takes just a few minutes to run it and it always speeds my system right back up. I'm not really sure what it cleans. It's not malware or spyware. I have other programs for that. But it works so I don't care what it's cleaning, lol. You might check that out.