Kbdrate
From wikinotes
the command-line program kbdrate affects the pause between your key beginning to repeat, and the interval between repeats themselves.
kbdrate -d 2.0 -r 2.0 ## test rate interactively
Once you settle on a speed that you like, you can
create a service-file for it:
#### /etc/systemd/system/kbdrate.service
[Unit]
Description=Keyboard repeat rate in tty.
[Service]
Type=simple
RemainAfterExit=yes
StandardInput=tty
StandardOutput=tty
ExecStart=/usr/bin/kbdrate -s -d 2.0 -r 2.0
[Install]
WantedBy=multi-user.target
####
sudo systemctl enable kbdrate.service
sudo systemctl start kbdrate.service