Overclock your CPU if it isn't and if you've got a good aftermarket CPU heatsink installed.
Are you running many applications in the background? Especially internet browsers (Chrome, Firefox, etc) can lower performance a fair bit.
How's the usage on the drive you've installed the game on while playing? You can check this easily in the task manager if you're running Windows 8 or 10.
Generally speaking, I'd agree with Supahos, it seems there's a problem somewhere, as you should be seeing higher fps with your config.