You either have the P8600 or the T8300 Intel CPU. Both are from 2008 (5ish years old), which means in computer terms that it's old.
Dolphin relies on single-core CPU speeds more than the GPU, so you're most likely hitting a CPU bottleneck.
Try one of the latest dev builds (current is 4.0-717). It has some speed advantages over 4.0 stable.
Also look into Bootcamp to get Windows/Linux on your Mac. The Nvidia drivers for OSX aren't as good as the Windows or Linux drivers are, so you could see some speed improvements using Windows or Linux.
You will probably want to start looking for some new hardware, though. Intel Haswell CPUs are the current best for Dolphin, but if you can wait for Broadwell, they promise even more speed
Dolphin relies on single-core CPU speeds more than the GPU, so you're most likely hitting a CPU bottleneck.
Try one of the latest dev builds (current is 4.0-717). It has some speed advantages over 4.0 stable.
Also look into Bootcamp to get Windows/Linux on your Mac. The Nvidia drivers for OSX aren't as good as the Windows or Linux drivers are, so you could see some speed improvements using Windows or Linux.
You will probably want to start looking for some new hardware, though. Intel Haswell CPUs are the current best for Dolphin, but if you can wait for Broadwell, they promise even more speed