You think that your bottleneck is the terminal emulator, but you are wrong. As the mosh people pointed out a few years ago, the output from the remote machine

You think that your bottleneck is the terminal emulator, but you are wrong. As the mosh people pointed out a few years ago, the output from the remote machine has to scroll for 5 minutes because it is all backed up in the SSH connection between your machine and the remote one. Your bottleneck isn't in the terminal emulator at all, and changing terminal emulators to whizzy new ones will not make any difference to it.