[modeless]

> you seem to be implying that the best a 60hz display can manage is 16.6ms of latency

Yes, if you control the whole software stack it is possible to do beam racing to get lower than one frame of latency (assuming low latency hardware for input and display panel scanout). But I'm talking about desktop/mobile applications. In general operating systems do not do this, and many actually make it impossible. Only very recently has it become possible to do beam racing in a windowed application (not using fullscreen exclusive mode) on Windows with recent graphics hardware with multiplane overlay and very, very few people have attempted to do it. I believe it is strictly impossible to do beam racing for windowed applications on macOS and Linux/Wayland. Not sure about iOS and Android.

[foxhill]

you don't need to "beam race" to achieve sub-frame latency - you don't need to be accurate. switching off vsync should, principally, be enough to achieve this.

otherwise, yes, modern APIs go out of their way to avoid the possibility of this (the dreaded "tearing" artifacts you see from the frame buffer being changed during the transmission of the video signal to the monitor). i don't believe older techniques like you've mentioned are at all possible today, and only really made sense to talk about when analogue displays were the norm.