Whats more important in HL maps the wpolys or the epolys? Also if my wpolys are to high can i change some brushes to func_walls and move the polys from wpolys to epolys?I noticed on vertsville the w polys are under 800 but the epolys go as high as 30k and it doesnt lag for me anyway.

you can use func_wall ents to lower the wpolys ( the HL engine can handle more epolys than wpolys) Also, for brushes that don't make up the outer wall of the map, moving them one unit above or away from other brushes keeps HL from cutting other brushes up. I've got an image somewhere, I'll post it when I find it.

Though, if you load your map with sv_cheats on, you can use gl_wireframe (1 or 2) to see how brushes are broken up.