Is it just me, or... (Performance)

I'm stuck using a HD Radeon 4650 card since my HD 6850 started crashing and dying a lot rather annoyingly. So my performance has taken a massive hit and I find it suddenly hard to play, particularly the sniper because of massive FPS factors in-game. It also doesn't help the sniper scope having too many fancy effects on it which kills my framerate, along with explosions and flak grenades suddenly taking off another 10-15FPS from 30-40 average just from being scoped.

However, one annoying factor I'm not sure about is how the glass in each map is rendered. I'm not sure, but I think maps with more glass to wall ratio have far more impact on my framerate, than with maps that have less, especially once other factors start piling up like bot spawn frequency increasing and artillery fire.

Steel Peel and LazeRazor there's always a bunch of glass knocking about. Ammo Mule and Grenade III has it better since there's a lot less glass. Spunky, asides from spawn, has practically none too (though I still hate that map anyway).

Don't suppose you could have an alternative glass renderer for old cards could you? Don't need the gloss effect, just a frame with a grey transparent surface would do.