Dolphin supports any x86 CPU, Intel or AMD. Simply because 3.0 works better than 4.0 for your AMD CPU does not mean Dolphin somehow abandoned AMD users. Dolphin became a more accurate and demanding emulator during that time, which means it required much more work from your CPU than before. People with fairly weak systems (yes, even Core2Quads) suffered from a drop in performance. AMD users were hit harder though because of the way AMD designs their CPUs is not suited to Dolphin's work load. Essentially, what Dolphin requires from a CPU, AMD CPUs simply don't deliver it as well as Intel does. This isn't the developers making Dolphin favor Intel; there is no "Intel-Only" code in Dolphin. This is just the difference of how two companies decide to engineer their products.
We've done benchmarks, and the conclusion is that while AMD's products does well in multithreaded situations, it's single-threaded performance lags behind Intel's with respect to Dolphin. It's not a matter of liking one brand or not; Intel CPUs have high single-thread performance and this is just the type of performance that an advanced emulator like Dolphin needs.
The newest development builds are actually faster than 3.0 thanks to recent optimizations, so try one of them. Again, it's not 4.0.2, it's 4.0-2xxx (replace xxx with numbers).
We've done benchmarks, and the conclusion is that while AMD's products does well in multithreaded situations, it's single-threaded performance lags behind Intel's with respect to Dolphin. It's not a matter of liking one brand or not; Intel CPUs have high single-thread performance and this is just the type of performance that an advanced emulator like Dolphin needs.
The newest development builds are actually faster than 3.0 thanks to recent optimizations, so try one of them. Again, it's not 4.0.2, it's 4.0-2xxx (replace xxx with numbers).