Espruino speed improvements - compiled JavaScript?

arr = new Uint8Array(1000);
for (var i in arr) arr[i] = Math.random()*256;

function slow(b,c) { 
  return b + c;
}

function fast(b,c) { 
  "compiled";
  return b + c;
}

function test() {
  t = getTime();
  console.log(arr.reduce(slow));
  console.log("Slow = ",getTime()-t);

  t = getTime();
  console.log(arr.reduce(fast));
  console.log("Fast = ",getTime()-t);
}

test();

gives:

 _____                 _
|   __|___ ___ ___ _ _|_|___ ___
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v72 Copyright 2014 G.Williams
>echo(0);
129986
Slow =  0.21045684814
129986
Fast =  0.03233909606

And that's just the start...