If it's that slow right from the start, then it's an issue with your computer settings or hardware. Have you tried running the game right after restarting your computer to see if it's an issue with your RAM being old and leaking memory?
I could say that it was a hardware issue a year ago, but I now even have a new PC that is way better and there's still not much change. I did try restarting it, but it was of no help.
