noel, I've also been running OS 7/8/9/X since poser 2.  some of the respondents don't know that, in OS X, the standard way to limit RAM usage on an app is within the app prefs, not via any system pane or pref.  just a few requests; please post screenshots of:

•  "about this mac/more info/memory"
•  "about this mac/more info/graphics/displays"
•  "activity monitor/system memory" with poser and firefox (stefan is referring to page-ins/page-outs above)
•  "activity monitor/system memory" with firefox et al., prior to starting poser