Raspberry pi 2 is slow on games emulated by mame like mk2. I am looking for the perfect hardware and the xu4 seems to have the cpu power to run everything smooth. However i am not willing to throw out the windows 80$ if i am not sure it works.
You will run into problems on any hardware that isn’t a raspberry pi. The only hardware retropie is stable on is the raspberry pi and even then we are still working on things. Though there is also some support for x86 which means if you have an old laptop laying around with Linux on it you can install it on there as well.