Dolphin, the GameCube and Wii emulator - Forums

I have been tinkering away for a while and had been noticing a large decrease in performance when enabling aliassing at any level, when having MSAA at 4x the fps drops to only 30% of what it was without MSAA enabled. the same goes for SSAA.
Whilst the frame drop is occurring, the CPU and GPU aren't nearly maxed out with a 60% and 40% load respectively.
the framerate goes from 60 to about 18-20, it's constant.

I have been stresstesting the hardware, with furmark for example, to see if the hardware has any issues... the pc performes well and as expected.
Has anyone got any idea what would be going wrong internally, or in regard to my hardware? i suspect something going wrong between dolphin and the driver.

Ayway, ways to reproduce:
turn on MSAA at any rate
Start your mario kart wii pal
vsync, HLE or LLE, IR 2,5x. all don't seem to make any difference with this issue.
Tried both lates stable and béta AMD drivers.

Could be of influence:
AMD r9 270 GPU
Intel Pentium K G3258 @4,2GHz dualcore, hasn't got hyperthreading.
Dolphin 4.0-6759
game i found most affected: Mario kart wii PAL, but every game is affected whilst the GPU is not nearly being pushed to the limit.

Just because the GPU isn't being "pushed to the limit" doesn't mean it's not the bottleneck.

Dolphin relies heavily on low CPU <-> GPU latency (because it's emulating an immediate-mode GPU), so if the GPU goes slower it will force the CPU to wait for it to be finished. This will lower the framerate even if the GPU isn't being used all the time, because then the GPU will sit doing nothing while the CPU does calculations (until it gets a new queue of commands to execute).

In other words, the longer the GPU takes to do something, the more it will slow down emulation, even if the GPU isn't "fully loaded".