That's weird, honestly I doubt it's the game, I never heard anyone having the game slow down. but just incase what are your specs of your pc.
Hmm.. sorry I can't figure it out why it's causing it.
I have been checking if there are any cause that maybe the game might be leaking memory without succes.
If you start up the game and press F2 on your keyboard you will get a FPS counter on top, during Syrianna's game can you check when you having a slowed down version what the counter says and shoot that to me.
Thank in advance