robinsonb5 has lately made some great speedups available on the CPU side, see here:
(pictures borrowed from user Fenio from atari forum)
I'm also fixing the AGA core, many games with sprite and color problems are being fixed.
The AGA core on the MiST board is not perfect, but we're (slowly) getting there
Any minimig-mist users here can post bug reports about non-working games / demos here (no account required):
Currently, I'm mostly interested in games that might have scrolling issues.