Thank you for your answer...I reinstalled the whole OS and then it started to magically work 
I did some testing videos running Dolphin with latest MESA drivers....
U can check the some videos here:
Raspberry Pi 4 - Raspberry Pi OS 64bit - Dolphin emulator
I also wrote a tutorial (some of the code is taken from you) how to install latest mesa drivers and Dolphin:
Dolphin emulator running on RP4B OS 64bit
And finally I came to conclusion that PI4 is just not powerful enough to run Dolphin on decent level....might be a bit better when Igalia finishes optimizing Vulkan driver....
Maybe we will have more luck with Raspberry Pi 5...

I did some testing videos running Dolphin with latest MESA drivers....
U can check the some videos here:
Raspberry Pi 4 - Raspberry Pi OS 64bit - Dolphin emulator
I also wrote a tutorial (some of the code is taken from you) how to install latest mesa drivers and Dolphin:
Dolphin emulator running on RP4B OS 64bit
And finally I came to conclusion that PI4 is just not powerful enough to run Dolphin on decent level....might be a bit better when Igalia finishes optimizing Vulkan driver....
Maybe we will have more luck with Raspberry Pi 5...
