I have a 655MB file with 1.5 million lines of lorem ipsum. I timed a cat in several terminal emulators. For this simple test, gnome-terminal beat xterm a little bit but wasn't anywhere close to the rest:

  foot             0m9.410s
  alacritty        0m16.881s
  konsole          0m36.737s
  gnome-terminal   1m1.096s
  xterm            1m16.919s

Foot has an page that explains when and why it's fast, and also when it's not, compared to alacritty.

https://codeberg.org/dnkl/foot/wiki/Performance