I recently acquired a debuff on my World of Warcraft's perfomance...

All of a sudden, my frame rates started to drop from a stable 60 to anything from 15 to 50.  Sometimes it'll be a stable 15-25 and other times it'll be a stable 40-45.

(Yes, yes.  I know enviroment plays a factor in your frame rates, I'm giving a aproximate)

My Computer's Specifications

• Intel(R) Core(TM)2 Duo CPU E6550 @ 2.33GHz (2 CPUs)
• 2048MB Corsair 800Mhz RAM, Dual Channel Interleaved
• NVIDIA GeForce 7950 GT
  PCI Express
  512MB
  256-bit
• SB Audigy 2 ZS Audio [E880]
• Windows XP Home Edition (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.070227-2254)
• Asus P5K Motherboard
• World of Warcraft Screen Resolution: 1600x1050

(I do know that the new shadow changes with the latest, 3.0 patch has a effect on your performance.)

Performance Settings (Experimentation in hopes of resolving my problem)

• Low
  I would still not get a stable 60 FPS, or even a 60, as a matter of fact.
  
  
• Medium
  FPS ranging from 25 to 50
  
  
• High
  FPS ranging from 20 to 40
  
  
• Highest
  FPS ranging from 15 to 35
  
  
• Highest (Shadows on lowest)
  FPS ranging from 20 to 40

Now... the strange thing is, I have always got a stable 55-60 FPS on Highest setting previously - I'm unsure when it all went bad.

I tried lowering my computer's overall temperatures (with a successful 10-15 Celcius drop from 55 to 40-45)
My GPU is currently averaging 40-50 Celcius.

Even with my attempts of lowering my computer's temperature, my FPS ceased to return to normal.

Now...  I am thinking of formatting my system and install the latest drivers.
But before I do that, I was hoping I would get some good advice before last-resorting to the more... drastic steps.