Still kinda curious & couldn't tell how much of your 292.9Mb was system & what was from which Poser source, so, as a benchmark, watched RAM usage here:

-20Mb used loading P4 app

-30MB more to load a 21Mb CR2 with Vicky & hair and 5 maps (equivalent to 3123312324 bits)

-60Mb more while rendering 600x600 with 3*1024 shadow maps