Yes, the CPU thread. I actually don't think that is the cause of the slowdowns in SMG though. It is almost all audio related. Maybe with HLE the CPU thread is the problem, but I think it is the HLE/GPU thread. Is there any way to test this?
Desktop:
OS: Windows 7 64 bit
CPU: Intel Core i5 3570K @ 4.4 GHz
GPU: EVGA NVIDIA GeForce GTX 550 Ti (Factory OC'ed)
RAM: 16 GB @ 1600 MHz
Dolphin Revision:3.0, 3.0-784, 3.5, latest 3.5
OS: Windows 7 64 bit
CPU: Intel Core i5 3570K @ 4.4 GHz
GPU: EVGA NVIDIA GeForce GTX 550 Ti (Factory OC'ed)
RAM: 16 GB @ 1600 MHz
Dolphin Revision:3.0, 3.0-784, 3.5, latest 3.5