Notice Chrome is slower in the first test because of the AJAX declarations. But honestly, who is going to be worried about the speed of AJAX declarations? Look at this comparison:

Chrome: Array object 131 Date object 30 Error handling 7 Math object 13 RegEx object 52 String object 41 DOM 51 Ajax declarations 295 Total Duration 620

Opera: Array object 172 Date object 47 Error handling 31 Math object 47 RegEx object 109 String object 63 DOM 31 Ajax declarations 62 Total Duration 562

If we assume Google can get AJAX declaration down to 62ms just like Opera (which seems perfectly reasonable, I don't imagine they had those in mind when considering speed), ten that would bring Chrome's execution time down to:

387ms!!

Assuming it can get a few more milliseconds down (it is after all only in beta stage, now that it's been open-sourced I can imagine a good couple of improvements will stream in), that means it's 1.5x faster than Opera! (which is hailed as the absolute king of Javascript execution)

Also, Opera does some kind of caching thing I think. On some of the tests (like Array and DOM), Opera consistently scored eiter X or 2X (e.g., 90, or 180). There is no way there could be a 2x speed difference just out of thin air like that, so I imagine it's some trick that notices when it can be sped up. If Chrome did that it could have the speed gain as well.