Actually, the INJ/REM system was developed so that file size could be reduced. The idea was not to inject all the body morphs -- only the ones you needed to accomplish the specific change. The morphs themselves can't be compressed for loading, as for some strange reason Poser won't load a morph from a zip file. Otherwise, the morphs are compressed -- they are pretty much as small as they can get. the 3rd gen figures are just a lot bigger in file size. That means that morphs wil be as well. It's terrible, but it's sorta the price of having the more realistic movement of the figure. The only thing I've found to actually help is to enable file and folder compression in the OS (windows 2k or XP), but the downside is that everything does load a tiny bit slower, and it's fairly usless is you have compression enabled for Poser already. P4 alone just doesn't really have much that you can do beyond that.

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)