Programming

You can definitely feel 100 ms in input response time. That's about what an analog modem's latency would be. I can tell you, that's very much noticeable on a telnet or ssh connection when you're typing (though to be fair, what matters there is really round-trip time, so one should probably double that).

On that note, if someone hasn't run into it, mosh uses UDP and adaptive local echo to shave down network latency for terminal connections, and might be worth looking into if you often do remote work in a terminal over a WAN. It uses ssh to bootstrap auth (if you're concerned about using less-widely-used thing what does network authentication, which I remember I was). I find that it makes things more pleasant, and also like some of its other features, like auto-reconnecting after an arbitrary length of time. One can just close a laptop and then reopen it a week later and the terminals function. Tmux and GNU screen can also do something similar

and in fact, I think that mosh and tmux are good packages to pair with each other

but they don't do quite the same thing, as they require (a) manual re-establishment of connection and are (b) aimed at letting one reconnect from different clients. It also displays a notice in the terminal if there's temporary network unavailability until it's re-established communication, so the user isn't simply staring at his screen wondering whether the software on the remote machine is being unresponsive or whether it's a network issue.