Know how I know you don't do Ordos raids?
I drop to 10 fps with a rig identical to the one Miele posted. The outdoor Sha raid was even worse, because of the aoeing of the adds.
But I don't think it has much to do with my system, but rather the game itself simply choking on all of the data it has to feed to the client. I believe it has to slow down to stay in sync. Turning off recount seems to make zero difference, but I've never tried turning off all mods just for shits.
25 man raids I don't ever see a problem, but I doubt I'm getting anywhere near 60 fps. The game simply will not allow it.
Mostly I just want to turn off others spells so I can fucking see though, yes. As a hunter I don't care so much but as a rogue HOLY FUCK was that getting annoying. Deathwhisper ghosts, ha ha, fuck you. It drove me to play mage again, and what a goddamn mistake THAT was.