(In reply to Brandon Wright from comment #95)
> For me, at least, it hiccups regularly every second and introduces
> noticeable latency. With dc=1 it's smooth

Thanks, I was able to reproduce the hiccups with vsynctester.com in windowed
Firefox.

> and more responsive.

Couldn't see a difference there (looking at how much the red dot trails the
mouse cursor on vsynctester.com). Ironically, the problem is actually that
non-DC can be too responsive, sometimes completing page flips in the same
vertical blank period.

https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/merge_requests/23
fixes it for me.