Emulator

Skies of Arcadia crashes even more often if you disable the framelimit, personally i would like this game added too.

Please do then, it's lightweight. I'll add it to the progress report as well as a game we're testing this experiment on.

Add Simpsons The Game here

Simpson's The Game doesn't run at all in dualcore right now, so why not? That's 6.

It's not critical, but PAL Paper Mario TTYD would benefit from it as well.
https://code.google.com/p/dolphin-emu/issues/detail?id=4957

Ok then, since jmc wants this merged soon i will wait a day for any further suggestions and then make a pr about it.

JMC4789 it runs with DC and SyncGPU and freezes with just DC

Just wanted to report that on my system (Intel e8400 - Nvidia 650gtx) "syncGPU" is so choppy that disabling dual core causes less performance hit; instead the option "fake completion" in game properties has almost no speed impact and still fixes for me the dual core hangs...anyway it's not a problem if I'm the only one with this behaviour, I will re-edit the ini's for myself.
Another curious thing is that I haven't been able to make crash dual core affected games using D3D exclusive fullscreen (instead when using OpenGL windowed/exclusive fullscreen and D3D windowed they always crash after a little while)...strange

Fake completion has limited compatibility and breaks a ton of things. Everything else is just coincidence.

What games are you having the slowdowns be that great? That's how Old SyncGPU was for me, but there is a new, customizable one that allows you to set how often it syncs.

With Metroid prime 3 the speed hit is not small, i am getting something like 30 to 40 percent lower performance during the game intro, perhaps it can be fine tuned? I need to check for a better value.

Actually no value makes a difference, i tried even
[Core]
SyncGpuMaxDistance = 40000000
and i get not a single fps of difference in Metroid Prime 3. The fps slowdown is pretty big and close to single core performance here.

Metroid Prime 2 doesn't have a big speed hit for me, can you confirm that? If Prime 3 is too big of a hit, we'll just leave it out. I get the logic there.

Ok made a pull request about it, 2666.

With default values I have huge slowdowns (previous SyncGPU version was better on my system); guess I'll have to mess with the settings then...

We should talk to degasus about it, this one should be faster. If it isn't, we need to figure out why.

Using
SyncGpuMaxDistance = 400000
SyncGpuMinDistance = -400000

brings back performance to normal for me, but also brings back dual core crashes as well, so I don't think the new option gives a lot of margin in messing with the settings...