Nothing is wrong with the G3258, it has the modern instruction sets necessary. Furthermore Dolphin doesn't seem to have many multi-threading options, so being a dual core affects very little. The higher clock speed is much better than having more cores.
Anyway, I just tried the most recent developmental revision as well. Same problem. I get 30 fps constant in WindWaker in 4.0.2 (50-60 fps if I unlock) with max AA, 1080p, DX11. In 4.0.5917 I get 18-20 fps with spikes to 30 fps. If I unlock the frame-rate it will spike to 50 fps instead of 30 fps. I deleted/moved my "Dolphin Emulator" document folder in both cases, and set the settings to be the same.
Edit:
Just did a benchmark. 4.0.652
6 minutes 58 seconds total time
2 sec Parse time
62 sec Photon time
5 min 54 second render time.
That doesn't look too far off from what people with i5's and other G3258's get.
Anyway, I just tried the most recent developmental revision as well. Same problem. I get 30 fps constant in WindWaker in 4.0.2 (50-60 fps if I unlock) with max AA, 1080p, DX11. In 4.0.5917 I get 18-20 fps with spikes to 30 fps. If I unlock the frame-rate it will spike to 50 fps instead of 30 fps. I deleted/moved my "Dolphin Emulator" document folder in both cases, and set the settings to be the same.
Edit:
Just did a benchmark. 4.0.652
6 minutes 58 seconds total time
2 sec Parse time
62 sec Photon time
5 min 54 second render time.
That doesn't look too far off from what people with i5's and other G3258's get.