This is excellent. Too often people guess at things when they could be more empirical about them. Ever since I learned the scientific method (I think 3rd or 4th grade) I was all about the 'let's design an experiment' :-).
Let me state up front that I have no idea why Wayland would have this additional latency. That said, having been active in the computer community at the 'birth' of X11 (yes I'm that old) I can tell you that there was, especially early on, a constant whine about screen latency. Whether it was cursor response or xterm scrolling. When "workstations" became a thing, they sometimes had explicit display hardware for just the mouse because that would cut out the latency of rendering the mouse in the frame. (not to mention the infamous XOR patent[1])
As a result of all this whinging, the code paths that were between keyboard/mouse input and their effect on the screen, were constantly being evaluated for ways to "speed them up and reduce latency." Wayland, being something relatively "new" compared to X11, has not had this level of scrutiny for as long. I'm looking forward to folks fixing it though.
Let me state up front that I have no idea why Wayland would have this additional latency. That said, having been active in the computer community at the 'birth' of X11 (yes I'm that old) I can tell you that there was, especially early on, a constant whine about screen latency. Whether it was cursor response or xterm scrolling. When "workstations" became a thing, they sometimes had explicit display hardware for just the mouse because that would cut out the latency of rendering the mouse in the frame. (not to mention the infamous XOR patent[1])
As a result of all this whinging, the code paths that were between keyboard/mouse input and their effect on the screen, were constantly being evaluated for ways to "speed them up and reduce latency." Wayland, being something relatively "new" compared to X11, has not had this level of scrutiny for as long. I'm looking forward to folks fixing it though.
[1] https://patents.google.com/patent/US4197590