Please read my last post in this thread. There are a lot of speed optimizations in progress, and a new build with possible lightgun support going in as early as next week Monday.
I personally see no problem with the current build with neogeo games, just make sure you set your colordepth to 15 instead of 32 to get around some errors that some neogeo games emit. There is no point in getting angry - if you would have just installed the current build and tested out some neogeo games you would find that most of them work very well. The only issue I can think of is changing the default color depth, and that is easy to do (and you probably won't know the difference).
If you want to help the authors out, make a list of games that run choppy now, also, submit as bugs games that do not work. Opcode is putting a lot of _speed_ (not memory) optimizations in at the moment and it will help to know what games should be retested after they go in so improvements can be noted. Impatience irritates developers more than anything - especially when they give so freely of their own time to work on things they distribute gratis.
At the moment, I know that Narc and some other games are choppy when sound is enabled. If you have other specific games that exhibit choppy behavior, please let me or one of the other MameoX testers know. I'm willing to bet you'll be very pleased this time next week with MameoX.