(OPTMZ equals optimization)

I mean like, for example

1 - 3 - 4

1 is the elevator
3 is the chamber
4 is the exit elevator

is there a way to like make 1 vanish out of the map when I get to 3? Like everything, textures, props, making it like a blank space.

Is there?

Read this: http://optimization.interlopers.net/
It's the best guide on how optimisation works. In your case, you'd want to have func_areaportals inside the entry door. Open the areaportal when the door opens, and Close the portal 2 seconds after the door does (so it has time to play the animation). You could also build a corner between the two locations, and use a diagonal hint brush.

Woah thanks, I was looking for something like this
(rather than watching tophattwaffle guide, because I can't focus while watching tutorials)