feeltty
quantifies the latency experience of a TTY.
go install github.com/coder/feeltty@master
$ feeltty ssh coder.c
connect 1278.56467ms
input sample size 32
input mean 98.824ms
input stddev 152.745ms
or local:
$ feeltty bash
connect 41.907167ms
input sample size 32
input mean 0s
input stddev 0s