Been having much the same issues, conform an item, poser freezes...delete a prop, poser freezes...load a background poser freezes.  Thing about it, is that it does not happen all the time but has been getting worse.  Swear it was a resourse issue but happens on the simple things (conforming hair to v4 no morphs). 

As there is a new PC in my future was wait and see but that may be another month and it is killing my interest in poser!

I will try some of the fixes and see what happens.