jQuery autocomplete for all place names in the UK
You can improve performance by using autocomplete function with this options:

$( "#location" ).autocomplete({
      source: availableTags,
      delay: 0,
      minLength: 2,
});


This library has  a 300 ms delay by default. So setting delay to 0 disables it.
minLength is for loading the matches after the users typed at least 2 chars, I don't think there is a point to load them when you have only 1 character.

Good luck