[8FS_Bulau]

It's not in Controls. When you are in the game, i.e. in a cockpit, activate the console by pressing Shift+TAB on your keyboard. A bunch of white text will overlay the screen. Now enter:

fps SHOW START

exactly that way, and the FPS counter will appear in red text at top of screen. Close the console with Shift+TAB again.

To stop the counter, do the same thing, except enter:

fps STOP HIDE