I assume that NTSC TVs have a refresh rate of 60 Hz, but even in games designed to run at that frequency, MAME can be choppy for one frame every 10 seconds or so through my TV.
I have MAME set to a refresh rate of 60, triple buffering is enabled, autoframeskip is off, and frameskip is set to 0. Still, every once in a while, the picture noticeably 'stalls' for a frame. This is evident in Fatal Fury's attract mode (the screen where a character stands on a mountain as the game's title scrolls by) and on Super Puzzle Fighter II Turbo's difficulty select screen (look at the scrolling "Puzzle Fighter II" background), to give a couple of examples.
It is not a problem with my system's performance, as I can run the two aforementioned games at 300+% unthrottled. Also, if I run both the TV and a computer monitor simultaneously and do a side-by-side comparison, the latter's picture will not stall when the former's does.
I'm guessing that it is either a problem with my TV or with my video card (nVidia GeForce series.) Has anyone else experienced similar problems with MAME through TV-Out?