Turbo on K10 processors (including the Phenom II) was a bit...broken to say the least.
As for CPU utilization, Dolphin itself only really makes heavy use of 2 cores, so it's more likely that you're seeing around 100% utilization on 2 of your cores and nearly 0% utilization on the remaining 4 cores, which can sometimes appear in things like the Task Manager like all 6 of your cores are running at ~30% load.
I personally have both a copy of F-Zero GX and a black edition Phenom II quad core, so I could easily check and see if the performance you're seeing is correct...though that's a bit hard to tell if you don't tell me what fps you're getting and where in the game those fps numbers were achieved.
Nevertheless, there's always the general stuff like make sure you're using the newest development build of Dolphin, and try using the vulkan renderer as well.
As for CPU utilization, Dolphin itself only really makes heavy use of 2 cores, so it's more likely that you're seeing around 100% utilization on 2 of your cores and nearly 0% utilization on the remaining 4 cores, which can sometimes appear in things like the Task Manager like all 6 of your cores are running at ~30% load.
I personally have both a copy of F-Zero GX and a black edition Phenom II quad core, so I could easily check and see if the performance you're seeing is correct...though that's a bit hard to tell if you don't tell me what fps you're getting and where in the game those fps numbers were achieved.
Nevertheless, there's always the general stuff like make sure you're using the newest development build of Dolphin, and try using the vulkan renderer as well.
Dolphin 5.0 CPU benchmark
CPU: Pentium G3258 @ 4.5GHz 1.24v
GPU: Intel integrated
RAM: 4x4GB Corsair Vengence @ DDR3-1600
OS: Linux Mint of some variety + [VM] Win7 SP1 x64
CPU: Pentium G3258 @ 4.5GHz 1.24v
GPU: Intel integrated
RAM: 4x4GB Corsair Vengence @ DDR3-1600
OS: Linux Mint of some variety + [VM] Win7 SP1 x64