Yes, I'm on KDE on X. gnome-terminal does not work (easily) on my distro so I cannot measure that. I did measure xterm which takes over a minute for both tests and also stresses out X. None of the other terminal emulators did that.

Still, I wonder if the terminal emulators could use less CPU and be faster if they refreshed only with the frequency of the monitor.

An interesting insight from the tests is that the execution speed of a program can depend on the speed of the terminal emulator.