If you really want to understand Ps2's then try this: make a box about 100x100x100 and build. After that you should have a pretty good amount of Ps2 faces added. Now build a 4x4x4 box then stretch to 100x100x100 then you should have no Ps2 faces at all. Trust me, I do this every single time when making big air brushes.
I have also noticed that when looking thru two portals that solid objects become invisible - is there a way around this hangup?
well a portal divides the rooms into small chuncks and only that chunck is rendered when looking at it, rather then the whole map being rendered. less strain on your GPU and CPU
and your problem i have no idea coz that never happens to me