In september of last year I bought an Asus K55VD-SX032H and upgraded my internet to a fast 80 Mbps, however, whenever I start downloading something either through uTorrent, Steam or whatever, the PC slows down. I'm not sure what could be causing the problem, the only real weak point I'd consider the notebook has would be the GPU but that has nothing to do with writing to the disk, and also the preinstalled Win 8. I can't remember if it has been behaving like this since day 1. Can safely assume it's not the antivirus as I have only recently installed Avast and only to try and fix this problem (no viruses found, though). Windows Firewall is turned on. The HDD is not cluttered at all, things are pretty evenly distributed between C: and D:, and I even ran several registry cleanups. When I check in the task manager, it ALWAYS shows Disk usage as 100-99%.