IPB will strip out unnecessary morphs from V3. You save your morphed figure to the library and load it into IPB. IBP will give you a pose or a face file that will load only the necessary morphs and spin the dials for you. I tried with a few and they actually became smaller than Vicky 2.
Memory and OSX: I did it as trial-and-error. Give Poser all the memory you have minus 100K or something. Try to start it. If it works - fine. Otherwise lower the amount of memory a bit and try again. The OSX programs will take care of themselves and they will always work.