We can get 10 msec inking latency with those on a 60 Hz display.
Also, native apps have a lot of options to reduce latency without any risk of tearing artifacts, and it's unfortunate that web apps don't have access to those options. The web has a long way to go to match native on the latency front and there really hasn't been meaningful progress in that direction.
I would like to experiment with pointerrawupdate and desynchronized again. But I'm currently relying on Emscripten's SDL implementation for input and drawing, and replacing or modifying that is daunting. After all, this is just a fun side project for me.
A much easier and more widely supported latency fix would be to use a blocking API like WebGL's ReadPixels to synchronize the content process and GPU process and defeat the deep frame pipelining that the browser usually falls into, at some cost to performance. I plan to try that first.