Single ssh-agent across multiple terminals. Put this in ~/.profile so it is executed after login

export SSH_AUTH_SOCK=~/.ssh/ssh-agent.$HOSTNAME.sock
ssh-add -l 2>/dev/null >/dev/null
if [ $? -ge 2 ]; then
  ssh-agent -a "$SSH_AUTH_SOCK" >/dev/null
fi

Vim sometime start slow if there are multiple user sesssions (not sure why)…

To kill user session when logout, change sudo vim /etc/systemd/logind.conf

KillUserProcessses=yes