Disabling AMD PowerPlay was the most promising workaround i found that should have helped.
Please make sure that the values in the MSIAfterburner.cfg are exactly like this:
UnofficialOverclockingEULA = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it
UnofficialOverclockingMode = 2
Then try the game again.
If it still stutters, please check if the GPU clocks down just before the game stutters.
To do that you can enable the On Screen Display of MSI Afterburner and watch the values while you run the game.
In order to do that open MSI Afterburner, click on "settings" and open the "Monitoring" tab.
Look at the middle section called "Active hardware monitoring graphs".
Select "Core clock" and check the "Show in On-Screen display" box at the bottom.
Do the same for "GPU usage".
The game should now show two values.
The first value shows the GPU load, the second one the GPU clock.
Now try disabling PowerPlay again using the MSI Afterburner config, and run the game.
If the GPU clock is low for a while, and than jumps to a higher value, while the game stutters, PowerPlay is still enabled.
If you are not sure how to interpret the values, you can make another video to show me the result.