tested on my C1 on scaleway:

  perl -e 'print "y\n" while 1' | pv -r > /dev/null
  [3.37MB/s]
  perl -e 'print "y\n" x 2048 while 1' | pv -r > /dev/null
  [ 425MB/s]
  yes | pv -r > /dev/null
  [11.1MB/s]