yes octree render also items behind the walls but not bsp , as far as I know
However my question was
The extensive use of zone and portals in the new generation game engines have something to do with the fact that the bottle necks , nowadays, mainly depend on the number of shaders , rather than on the number of tris or they are simply more efficient culling algo's ?
I mean, as long as , you reduce the amount of data to be sent to the render pipeline than you should get a benefit, I suppose, in any case
On the other hand you must take into account the cost of the algo itself in term of CPU cycles