WoW being low framerate after reformatting the computer

[galzohar]

I recently reformatted my computer, reinstalled the OS, WoW, and all relevent drivers (motherboard, sound card, network card, soundcard, graphics card and monitor). When I ran WoW with no addons or macros it ran a LOT slower (FPS-wise) than it used to before I reformatted, and before I reformatted I had a LOT of active addons that did not affect performance noticeably at that time. Also when I reinstalled the addons I didn't notice additional performance drop but they remain extremely poor.
I used to be able to run the game with default color settings, 1024X786 resolution and max terrain distance relatively smoothly, and now I get terrible framerate with every possible graphic setting set to the lowest quality / best performance possible.
I've even cleaned the spyware that somehow invaded my computer since the reformat and noticed no improvement, so that's not the issue.

Please let me know what can I do to make WoW work like it used to... Thank you.