Ive had a few cases where it was the OS that slowed my comp down a ridiculous amount. After reinstalling it, and starting from scratch, everything ran much smoother. Also, as many here know, recently I had hardware problems as well. Both can be such an annoyance to deal with. RAM, hard drive, processor, OS, processes... all of it can bring your computer to its knees. I wish it was that only ONE thing could slow down your computer, making troubleshooting so much easier (9+ hours of trying to get my computer back up to snuff agrees with me).  I recently was experiencing similar problems. My i7 was slower than MY netbook as well lol. Now, everything is going pretty smooth. However, there are some hiccups still, and so I need to go back to more diagnosing.

I also remember years back, on my Compaq Presario with its like 200Mhz or so, it'd buckle whenever it started up if I didn't immediately turn off SW Doctor. Anti-virus software often seems to be such an annoyance. My netbook was experiencing like a full minute of slowdown upon booting up, and I figured out it was the preloaded antivirus trial software that came with it.

Wasn't really trying to change the topic to be about me, but even with as little experience as I have with putting together computers, I can understand where you are coming from.