The fastest JavaScript fizzbuzz I've seen. Ported from https://gist.github.com/ggilder/2893724, which also explains what's going on.

fastest_fizzbuzz.js

var acc = 810092048;
var aMillion = 1000000;
var number = 1;
var log = function(value) {
  console.log(value);
};


function bitwiseFizzBuzz(i) {
  var c = acc & 3, a = 'fizzbuzz';
  if (c === 0) {
    a = i;
  } else if (c === 1) {
    a = 'fizz';
  } else if (c === 2) {
    a = 'buzz';
  }

  acc = acc >> 2 | c << 28;
  return a;
}

while (number <= aMillion) {
  log(bitwiseFizzBuzz(number));
  number++;
}

Run it on jsfiddle and test it on jsperf