usb stick rotates faster Resident Evil 4

I have no real problem, as you will see, but as far as I am surprised at the highest point, I'm wondering if someone could explain:

Here, I decided to replay resident evil 4 on my new pc because in my old age did not play with the patch that makes this game acceptable graphically on a PC (my old computer rowed with the patch fixes).
So I installed the game and patch and it was slow as before with my old pc! for info I have a core 2 duo 3.16 giga and a graphics card that kills (nvidia gtx 260) and 4 gigabytes of ram, so no reason why this game a little old train set. I tried to reinstall, to see directx, etc ... and eventually realize that the game runs at normal speed when my USB KEY IS INCLUDED IN PC, IT IS THAT THE GAME IS GOING TO NORMAL SPEED!

how you explain that?

thank you

One explanation could be that your game uses a temporary disk important and if you had installed on the same hard drive, going back and forth between the game and the temporary directory can slow the game and more so if your operating system is installed on the same disc.
Another explanation, your drive should be defragmented to win a bit of speed.

Be careful all the same with your USB key, after a while it can still heat up and eventually could crash. I advise you to make backups of your files from time to time on your hard drive.

my hard disk is not fragmented. but as you say my game is installed on the same hard drive that my operating system. Perhaps there is also the problem, as you said, the temporary directory and return, etc ... but why and how my usb key can play a role in there?

The game of swapping with 4GB ram? (or even 3.2Go ...) That would be amazing ... Perhaps your usb key has other virtues ... Try to make brew, you'll get perhaps a herbal tea that can cure all

More seriously it has nothing to do with ReadyBoost?