Hmm, interesting.

so if increasing the lowside pressure actually makes it easier on the compressor, why do people try to run the suction side in a vacuum? to reduce the boiling point of the refrigerant?

I guess its all a balance, you find what the compressor will do at "normal" setup, then lower the highside temp to make the compressor not work as hard, then put the lowside into a vacuum to reduce the boil point, thus putting the compressor load back up again, hopefully to where it was before.

Am I right?