Is Walkable - how does it work?

First off, if you don't for certain what exactly causes it, please don't respond. I don't like taking random stabs at the problem.

I've been working on a very simple building generator; it creates buildings on small sections of walls. The example is at the bottom and also add clarity to my problem.

My problem is the option "Is Walkable" for destructible are incredibly cpu-intensive when used in large numbers (upwards of 2,000+?), even if these destructible are on the other side of the map it still seems to have an effect on framerate especially when the units are moving.

With no units the option "Is Walkable" has little effect on fps.
With only a few units in the camera view the framerate drops easily to 45~ when still, and down to 30 when moving.
With many units in the camera view the framerate continues to drop, easily getting less than 10.

When the units leave the camera view framerate returns to normal (64~ for me)

I have tried figuring out what causes this and have yet to have much luck.
An empty or non-existent file causes normal framerate.
A simple plane causes bad framerates on par with the regular wall.
A complex sphere causes bad framerates on par with the regular wall - even though made of many more polygons


In short: How does wc3 set a units height when walking over a destructible set on "Is Walkable" and what are ways to reduce this?


(All models used in the below map were made by me - textures curtousy of CG Textures.
You can use the walls and textures in any way you like - no credit to me. If you want the psd of the textures for easier editing (and higher quality) email me at (username)@hotmail.com
with (username) replaced by my wc3c username. I get enough spam as it is!)
-If game crashes while generating buildings retry even if seed values are the same. Haven't tracked this down but 99% certain it's trying to place destructables outside the map
-If you do your own testing make sure you disable random seed, so building design is consistent.

If the number of polygons per destructable does not affect framerate while the number of destructables does, try using fewer destructables with fewer models.

Hmm doesn't WE generate a "height map" when saving? Guess I read s.th. like that in the GMSI thread.

I think the "is walkable" option doesn't necessarily drain any extra peformance.
But as Anitarf said destructables consume quite some power... one of the reasons I chose doodads as pathing blockers in my map.

At TheHelper at least i think they made a system that deletes the pathing blockers but retains their pathabilities. I think they used some of the features from WEU.