Some results to compare speed of different autocomplete methods
Ruby 2.1.1
Thin Elapsed time for controller autocomplete: 5.612114202 Elapsed time for rack app autocomplete: 2.663584515 Elapsed time for rack middleware autocomplete: 1.946385753 Unicorn Elapsed time for controller autocomplete: 5.695448048 Elapsed time for rack app autocomplete: 3.419353762 Elapsed time for rack middleware autocomplete: 2.720414571 Puma Elapsed time for controller autocomplete: 5.470961704 Elapsed time for rack app autocomplete: 3.442538771 Elapsed time for rack middleware autocomplete: 2.439292391