Whichever...

With a BT headset, when the phone rings, it needs to activate CPROG.EXE, load the BT*.dll, and get your bluetooth headset working.

That's not a lot of "time" for an xscale-based concept to bump up the CPU horsepower.

Dave's utility is nice... and it's let me see I don't want the processor running any lower than 300MHz (worst case), 400MHz (normal case).

In other words, if it saves any battery time, it does so at the expense of missing valuable incoming calls, SMS, etc.

Ehud