Originally Posted by
evn
Pretty much what the above poster said. Even todays most high-end AMD processors perform somewhere on par with 2 year lower-tier Intel hardware when it comes to warcraft. It's perfectly serviceable for other games but warcraft stresses areas that AMD just isn't good at handling.
The major performance penalties are imposed by SSAO, Shadows, View Distance, and Multisampling. Dropping those may help your frame rates for many things but you'll probably always experience some choppiness when you're doing large group content.