> Won't it mean that video games are going to be completely unplayable
Even on my x.org desktop without compositing or any other source of extra frame delay, just turning on vsync in-game utterly destroys my ability to play Super Hexxagon[1]. If Wayland is adding additional frames of latency, I'll have to add that game (and probably any other rhythm game) to the list of reasons I cannot use Wayland.
Yes, actually Super Hexagon was one of the games I play and was thinking of when I made my comment. I find it difficult enough to play with my older computer using Optimus, but when I tried it on Wayland there was at least another 100 ms of latency. It was unplayable to the point I feel pretty sure even a TAS couldn't keep it going for long. Compositing everything with no way for apps to bypass it when necessary is profoundly stupid.
Even on my x.org desktop without compositing or any other source of extra frame delay, just turning on vsync in-game utterly destroys my ability to play Super Hexxagon[1]. If Wayland is adding additional frames of latency, I'll have to add that game (and probably any other rhythm game) to the list of reasons I cannot use Wayland.
[1] 76:37 on hyper hexxagonest!