>>2764648In very recent iterations of MAME, specific chips like the TMS3203x used in some of the 90s Midway machines, now have their own seperate ROM dump that doesn't show up in the games list.
Its possible certain games you have may use those. To check, run mame on a command-line/terminal window.
Type "mame" followed by the name of the ROM (the zipfile) you are trying to play. If it dumps back to the prompt instead of starting a game, it will tell you what ROMs that are required failed to load.
>>2764668In case someone is actually experiencing heavy input latency with MAME, try using Retroarch and download the latest MAME Git core from the built-in Online Updater.
Then in RetroArch, go to Settings->Driver->Input Driver to change the backend API for input handling to something else other than what it was set to. Some systems/configurations work better with a different API.
Also, disabling VSync helps. Autoframeskip can mess it up, too.