Why Mem Usage increases when shrinkwrap is selected?

Hello

I use shrinkwrap in my ProE 4 model assemblies, but recently

I noticed that when a shrinkwrap is open (active window), each time this part is

selected (using smart) the Xtop process increases 3000Kb of Mem Usage;

and I need to close ALL and erase not displayed parts to free memory.

The Xtop process does not reduce when I deselect or close only the shrinkwrap.

That doesn't happen when the same part is selected in an assembly.

does any body could explain it please??

what can I do to avoid it??

thank you

Gustavo C.