Dolphin was a pretty mixed bag at the time. I got through Xenoblade Chronicles on that system, but I remember one of the regions on the mechonis(?) would only do like 7fps at best, but other areas would do 20-30. But monkeyball worked pretty well, as did some of the other GameCube games.

But I was using that system when Sandy Bridge was already out, and still using it when Haswell came out, because I was a broke student. So the software may have been a little more developed than when you were messing around with it.

Also I don’t think the e8400, or any of the core 2 duo/quad cpu’s had hyperthreading. I know the Pentium 4 had it, not sure about the Pentium D