While running emacs over a modem to arpanet or dialup, I got into the habit of regularly typing ^A ^E to pace my cursor back and forth across the current line, to keep the connection and emacs warm.
(Like a caged leopard or mad scientist pacing back and forth.)
I could feel how responsive the connection and emacs were over time by the delay between typing and seeing the cursor move. Both the network and emacs contributed to the feeling:
There was the overall "weather" of the network: sometimes sunny and fast, sometimes sprinkled with light delays, and sometimes stormy congestion. Then there were occasional incidents that came and went, like network hiccoughs and emacs paging and grinding. And then there was the overall load of the system, which gave you the baseline delay (which gave it a very tactile day -vs- night feeling, since you got more of the machine to yourself during the night when it felt snappy, but it felt sluggish during the day).
It really felt like either the network, emacs, or both would fall asleep if you didn't keep them warm and lavish them with attention.
A VAX 11/780 running Gosling Emacs over a dialup had a very different feel than a PDP-10 running ITS Emacs over the arpanet. The busy VAX was bursty and had a lot of bumpy paging -- you had to keep your buffers warm or they would all get paged out and it would take a long time to wake back up, but there was no network delay from the direct dialup. While the PDP-10 ran smoothly like a well lubricated steam locomotive, sometimes slowing down when busy, but hovering around same speed instead of bursting, and the delay was mostly the feel of arpanet congestion and imps dozing off.
(Or so I imagined. I had a lot of time to sit and think while waiting for the cursor to move again, and the mind wanders and wonders what's happening...)
TOPS-20 had a wonderful ^T keyboard interrupt that you could
type to instantly show the system load and time. (But of course you couldn't use that in emacs, which puts the tty into raw mode.)
Somebody at the university implemented ^T to 4.2 BSD on the cs department's busy VAX 11/780, by modifying the tty driver. But initially, there was no limit to how often you could type it, and calculating the current system load wasn't a trivial operation.
So on a fast terminal, if you held down and auto-repeated ^T, it would bring the entire system to its knees, and you could watch the load go up and up and up as you caused it to! Very satisfying indeed.
Eventually they put in a one-per-second limit on ^T.