Ok, a little weirdness here, implicitly declaring the variables as Local speeds it up a little, putting strict in slows it down slightly (but still faster than the code at the top of this thread).
After 3 runs:
With strict: approx 3.8
Without strict: approx 3.6
*EDIT*
I just tried it again and with strict was slightly faster this time.
Strict Local t#=MilliSecs() For Local i=0 To 10000000 Local result# = Cos(i) ^Cos(i) Next Print Float(MilliSecs()-t#)/1000
After 3 runs:
With strict: approx 3.8
Without strict: approx 3.6
*EDIT*
I just tried it again and with strict was slightly faster this time.