Terminal and iTerm uses whatever method they are using to ssh that basically slows down if the network connection to the server is slow. All the commands I type would show up on the screen seconds later. Is there a client I can use where the command would render faster on screen regardless the speed of the network?
As you cannot use mosh, your choices are very limited.
You can use the following perl-based wrapper for the standard OpenSSH command supplied with macOS to enable line-mode:
Remember to read the instructions before use: