Yeah, I just came to the same conclusion.

Win10 2004 timer changes are breaking.

Timer frequency adjustments (timeBeginPeriod) don't seem to affect Windows timers in the same process like they used to do!

Again. In Win10 2004, if you do timeBeginPeriod(1), timers in the same process (other than using the deprecated multimedia timer) seem to only trigger every 15-16 ms or so instead of 1 ms.

This is bad.

As a sidenote about Win10 2004, after timeBeginPeriod(1), Sleep(1) seems to take about 2 ms per call. Or at least it seems to take about 1950 ms to call Sleep(1) 1000 times when I tested it. Confusing.