Hey gaes...how to see my fps?

r_displayinfo 1 is basically hard-coded not to work. I wouldnt be suprised if the data required to output the info isnt even in the game.
You can, however, use other programs such as FRAPS (all cards) or EVGA precision (for NV card users) to measure your FPS.

fraps also

http://www.fraps.com/download.php

Approved, Fraps has always been nice for checking FPS.

Use console in-game like you use cheats.
Fraps or MSI Afterburner or Evga Precision(powered by RivaTuner).

If you have logitech g-keyboards you can track stats there.
It will not impact on graphics but will take some ram & cpu power.
Stat tracking works with some apps. Doesn't works with FRAPS(in g-keyboards).
Monitoring temperature and stuffs also eats lots of resources.