G2 has a built in frame rate display.
To set it up,
click on VIEW,
slide down to GADGET,
click on EDIT GADGETS,
click on the ADVANCED NAVGUIDES tab,
scroll way down the list to find SYSTEM: FRAMES PER SECOND,
click on the square box to put a checkmark in there,
click on the OK button to save.

To get the frame rate to appear on the screen,
click on VIEW,
slide down to GADGET,
click on ADVANCDED NAVGUIDES.

Or just hit the number zero key.
(note: the zero key on the calculator keypad won't work.)