ビットカウントの速さ

ビットカウントで、分割統治法と呼ばれるものと、テーブルを使ったものとではどちらが早いのかテストしてみました。以下JavaScriptでのコード

function hammingWeight1(number) {
  number = (number & 0x55555555) + ((number >>> 1) & 0x55555555);
  number = (number & 0x33333333) + ((number >>> 2) & 0x33333333);
  number = (number & 0x0F0F0F0F) + ((number >>> 4) & 0x0F0F0F0F);
  number = (number & 0x00FF00FF) + ((number >>> 8) & 0x00FF00FF);
  return   (number & 0x0000FFFF) + ((number >>>16) & 0x0000FFFF);
}

var weightTable = [0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8];

function hammingWeight2(n) {
  return weightTable[n>>>24] + weightTable[(n>>>16) & 15] + weightTable[(n>>>8) & 15] + weightTable[n & 15];
}

var d, i, t1, t2;

d = new Date;
for (i = 0; i < 100000; ++i)hammingWeight1(4294967295-i);
t1 = (new Date).getTime() - d.getTime();

d = new Date;
for (i = 0; i < 100000; ++i)hammingWeight2(4294967295-i);
t2 = (new Date).getTime() - d.getTime();

alert([t1,t2]);

Firefox3.6ではテーブルのほうが早かったですが、それ以外は計算のほうが早かったです。
C言語で書いてWindowsで実行したらテーブルのほうが早かったです。