First of all, the emulator developers recommend Haswell CPUs, since Dolphin gets almost 25% improvements in speed over Ivy Bridge at the same clocks. This was true as early as Dolphin 3.0, long before any of the recent performance optimizations. Even with Haswell though, the recommended CPU is i5-4670 or better.
Second, two of the developers, comex and Fiora, have been on a tear recently. Star War Rogue Leader has a doubling of speed thanks to Fiora, for example. comex has made smaller improvements, around 10-16%, but they affect all games, not just MMU games like Rogue Leader.
Third, you probably did use too much AA, I do it all the time, .
Just the August and September optimizations have yielded a minimum 40% improvements to most games and as high as 110%.
Here is the September changelog for Dolphin. Some hyperbole in the descriptions but you get the picture.
https://dolphin-emu.org/blog/2014/09/30/dolphin-progress-report-september-2014/