Someone, SVDL I think, has a python script which strips out all unused (zero-value) morph channels from a figure in memory. It seems to work on props attached to the figure as well, and even strips out morphs from non-injection figures. (I haven't tried it on V4.1, but it works on A3 and H3.) This will dramatically reduce the memory used by poser prior to rendering. I've found that my biggest problem is that when I have six or eight figures, each with six or so props, clothes, hair etc., that the regular P7 program is running at about 1.7 MB. Next time this happens, I'll try using the morph stripping script.