I've tried schrodinger's file now. Very helpful. However, there were a couple of problems with it that masked some of the microstuttering. Firstly, it had vsync turned on. Like I wrote earlier, having vsync on greatly reduces microstuttering (in my experience), so it's probably best off when trying to test for microstuttering. Also, vsync artificially clamps certain frame times, so it's likely to get in the way of these sorts of measurements. There's little need for vsync in a windowed application anyway, since you should never get screen-tearing in windowed mode anyway. The MFA also had "machine independent speed" turned on. I don't know exactly how this affects microstuttering (if at all), but I figure it also may artificially clamp or skip frames, so best to leave it off for these tests.
Also, the ball was moving very slow - 1 pixel per frame. This just makes it way harder for anyone to visually spot microstuttering, whether with the naked eye or a camera, because everything looks naturally smoother at such slow speeds. For example, if one frame gets skipped, a ball moving at 1 pixel per frame will move by 2 pixels, while a ball moving by 6 pixels per frame will move by 12 pixels. Both cases skip exactly one frame, and may report the exact same microsecond frame duration.....but the latter will be much easier for the naked eye to spot, since it's easier to see 6 pixels than 1 pixel.
I've uploaded a modified version that speeds up the ball and disables vsync and machine independent speed. I also added an orange counter, so that if there are skipped frames, the counter will also show evidence of them.