Based on all the performance metrics I've seen and various different benchmark videos on Youtube, it looks like MW2 is a severely GPU limited game. My CPU render time is only 3ms at 3440x1440p with a Ryzen 5600x.

You'll be able to drop into the FPS armed with any CPU that's at least as powerful as the Intel Core i5 2500K or AMD Ryzen 3 1200, so long as you pair it up with 8GB of RAM.