no key repeat in Xquartz (x11)
From @jaykru on SuperUser.SO (https://superuser.com/a/414513/152522): 


  Did some more searching and discovered in recent updates the key
  repeat rate for x in OS X is set at some odd value. Anyway, to whoever
  else may have this issue, run this in your shell:

    xset r rate &lt;milliseconds_before_repeat&gt; &lt;repeats_per_second&gt;

  
  Or just xset r rate to reset the keyboard repeat rate to default X
  settings (i.e: something sane.)