Thanks for the help ive know fixed, it the problem was i had a Saitek gaming keyboard and making the game lag. Here's how to fix, (not my guide)
What you describe sounds exactly like what I went through after I started using a Saitek gaming keyboard. The slow fps in menu and game wouldn't go away until I applied a fix I found at the Saitek help forum. No other games were affected.
Not sure if you are experiencing the same sort of thing. But for what it's worth my fix was:
"In Device Manager - Click the plus sign next to Human Interface Devices in the list of devices and you should see one or two (maybe more) entries called USB Human Interface Device. You need to disable one of them by right-clicking it and choosing Disable from the drop-down list of options.
Note: If you have only two such entries there in Device Manager then only one will be able to be disabled - the other will have the disable option greyed out in the drop-down list when you right click it. If however you have more than two such entries in Device Manager then you will need to ewnsure that you disable the correct one. This is done by double clicking on each one in turn and looking at what it says next to Location on the Properties page. The one that should be disabled will say USB Gaming Keyboard Pro next to Location. Once you have disabled that then try the game again and it should work fine."