Turn off TimerInit() ?

Near the beginning of my app, I have

$startTime = TimerInit()

Then I test it in a loop, taking action if it runs too long, then don't bother with it again.

Is there:
(1)  a way to turn it off?  (I'm not using #include <Timers.au3>, just the built-in functions.)
or
(2) any performance hit having an unneeded timer accumulating time for the rest of the time the app runs?

Thanks!