Neither Konsole nor GNOME Terminal are as lean and fast as (U)XTerm, however on day to day use, I fail to see input latency on these. I generally use 60-80WPM depending on what I write and how concentrated I am, and there's no noticeable lag from my perspective.
GNOME terminal was visibly slow in the days of yore, but given that the libraries powering these are already accelerated, I don't think the difference between these "accelerated" terminals are as big as touted w.r.t. GNOME Terminal or KDE's Konsole.
To be fair I haven't tried gnome terminal in some years so maybe it's improved. I have used konsole (well, yakuake, but same thing) more recently and was minorly annoyed by the latency, particularly when scrolling in emacs/etc. I have since swapped out yakuake with kitty with tdrop for the "quake mode" effect.
Yes, Yakuake uses the same Konsole framework, but they might lag behind in terms of framework version IIUC. Konsole supports more features than Yakuake and feels a bit smoother to me since I drive both daily.
Love to collaborate and make some tests with you, too.
GNOME terminal was visibly slow in the days of yore, but given that the libraries powering these are already accelerated, I don't think the difference between these "accelerated" terminals are as big as touted w.r.t. GNOME Terminal or KDE's Konsole.