perf
Some numbers on a MacBook Pro 2.53 GHz Core 2 Duo
commit Firefox 3.0.15 Safari 4.0.3
bb5899c56e33716db724cb60a5120b91f5fccdeb
28 ms/instantiation
15.02 ms/instantiation
2847c1cf1a2874e9fe56b5749e6e105e37bb086a
49.27 ms/instantiation
24.48 ms/instantiation