JC Whitney catalogs used to carry add-on vacuum switches that would cut off power to the A/C compressor if the throttle vacuum reached a certain point during hard acceleration. Once the vacuum came back up, it switched the compressor back on.
In those days (30 years ago), it made a huge difference to click off the A/C for hard acceleration. With a car full of passengers and a trunk full of luggage, it wasn't unusual to have to shut off the A/C to make it up a steep grade.
I'm not sure I've ever noticed a click or RPM drain on my new MBs; maybe they're variable compressors tied to the ECU?
Many would say it wouldn't matter... but it does. A/C only kicks off when
> you do a full hard acceleration. Half throttle or anything less than
> triggering your kickdown switch would not turn A/C off momentarily. >
> By switching A/C off, you unload the engine from the extra
> strain/friction/load... yielding quicker acceleration. It really does make a
> difference...
>
> Try it yourself... drive the car normally with A/C on... and do some
> spirited acceleration. Then do the same driving with A/C off... you will
> notice quicker and better response from engine.
>
>
>