quick hideentity question

I am creating a large street level.
Several buildings are there for effect only whereas one or two will be accessible.

If I create a mesh for the generic streetstuff
a second , third mesh etc for each accessible building
and separate interiors etc will this make a difference ?

When outside all exterior meshes are drawn
when inside the relevant interior is drawn and everything except relevant internal is hidden.

Does this make sense ?
Will render speeds be improved ?

yes it will.
something like portal rendering
Create a hidden box inside the doorway and
a hiddenbox outside of the doorway.
if you enter box outside then show all meshes in Zone1 hide zone 2
if you enter the box inside then show all meshes in Zone 2 hide zone 1

if you are in zone 1 and enter the box for zone 1 then do nothing