hmm, well 4,000 polys isn't much at all, unless you have a ton of colision polys and linepicks being calculated, or way too many textures and entities being drawn at once.
in my xperience linepicks, collision, high number of entities, or too many surfaces cause the biggest hit.
regular shinyness on your brushes do little, if your using dynamic cubemaps though, where it renders a cubemap in realtime per frame or every other frame that will have a pretty big hit on your game as if they were dynamic it would be like rendering your scene an extra 6 times per frame. Some brushed need more than 1 pass if they have complex multitexturing on.
can't really say without seeing what your game looks like and what it's doing.
in my xperience linepicks, collision, high number of entities, or too many surfaces cause the biggest hit.
regular shinyness on your brushes do little, if your using dynamic cubemaps though, where it renders a cubemap in realtime per frame or every other frame that will have a pretty big hit on your game as if they were dynamic it would be like rendering your scene an extra 6 times per frame. Some brushed need more than 1 pass if they have complex multitexturing on.
can't really say without seeing what your game looks like and what it's doing.