the only way you can nearly get the speed of a real dualcore is:
1. open your taskmanager, go to processes, rightclick dolphin.exe and use the option below "set priority" (this option is called "Zugehörigkeit festlegen..." in Germany)
in this menu select only CPU "0" and "2"
2. and last but not least disable "Lock threads to cores" in the config of dolphin. (this could also help if you are not doing step #1)
1. open your taskmanager, go to processes, rightclick dolphin.exe and use the option below "set priority" (this option is called "Zugehörigkeit festlegen..." in Germany)
in this menu select only CPU "0" and "2"
2. and last but not least disable "Lock threads to cores" in the config of dolphin. (this could also help if you are not doing step #1)