Variable font transition jerky in Windows

I’m not even sure how to tag this. When I test my variable font in Windows 10 Chrome and Edge, I see a jerky transition instead of the smooth transition I see in Firefox, Chrome and Safari for the Mac. I don’t know how to make an animation small enough to upload here, so here’s a demonstration I uploaded to YouTube:

The problem can be seen in practically any glyph but is especially noticeable with the lowercase g.

Has anyone seen a problem like this? What’s more likely: something wrong with my axes or Windows being buggy? (so far I have no way to test in Illustrator for Windows)

I’ll add that, playing with the fonts on Axis-Praxis (in Chrome on the same machine), I see the same effect with most fonts there (but not with Avenir Next).

Windows does more rounding. And I think it also depends on your font smoothing settings.

The (Microsoft) spec for the Optical Size axis says, “The scale for the Optical size axis is text size in points,” so I made my opsz scale 6-18. If the MS rasterizer is, say, rounding the opsz to int, it might be a problem. I see some fonts apparently ignoring the point-size advice, e.g. Amstervar 10-72, Voto Serif 12-72 (at least, I see no reason to design for 72-point type!).

On the other hand, Zeitung Pro runs 8-20.

Is it better to have a wider range of numbers in an axis?

I am not sure, but I do not think so. It has to do with the rasterizer and the way it creates the pixel image for the screen. On Windows, there will be less anti-aliasing, hence the perceived jerkiness.

I suppose there’s nothing to be done about it, alas. Thanks very much for the info.