> 3) Macintosh Plus/512 speed fixes to resolve this issue
A lot of MAME's problems with Mac emulation can be traced back to the flawed VIA shift register. Vas has a rewrite planned but I don't think I've heard of any progress on that front lately. Olivier Galibert also did a WIP modernization of the IWM floppy controller which has been pushed to a Git branch.
> 7) Votrax/SC-01 improvements
The new emulation really stands out as one of the most unfortunate MAME regressions. The fatal flaw seems to have been ignorance of the bizarre and idiosyncratic method by which the SC-01 is clocked.
> 10) Improvements to high-profile console drivers such as nes (more accurate ppu), > pce-cd, atari 5200 and n64 (speed optimizations)
The Sega Genesis VDP emulation has often been noted as being in need of a good full rewrite. The MT bugs just keep piling up.