According to http://code.google.com/apis/v8/run.html Chrome’s javascript engine is 10 times faster than Firefox 3.0. 1152 (Chrome) vs 110 (Firefox). Although they both take about 8 seconds to run on my machine. This is the danger of benchmarks. You can optimise for any benchmark but the real trick is in choosing which benchmarks to optimise for. And you ignore ‘user time’ at your peril. As a browsing human, I don’t really care how many milliseconds New and Improved Browser shaves off Brand X’s benchmarks. I care about how long I’m waiting for the hourglass to disappear or the spinny thing to stop spinning.

As a developer, of course I went off and found the webkit benchmark. Results below, in all their ugly unformatted glory:

TEST                   COMPARISON            FROM                 TO             DETAILS

=============================================================================

** TOTAL **:           2.28x as fast     5387.6ms +/- 0.6%   2358.2ms +/- 0.2%     significant

=============================================================================

  3d:                  3.69x as fast      621.6ms +/- 1.1%    168.6ms +/- 4.0%     significant
    cube:              5.35x as fast      229.0ms +/- 1.3%     42.8ms +/- 11.5%     significant
    morph:             2.88x as fast      205.4ms +/- 1.4%     71.2ms +/- 5.7%     significant
    raytrace:          3.43x as fast      187.2ms +/- 2.1%     54.6ms +/- 3.1%     significant

  access:              6.93x as fast      885.6ms +/- 0.9%    127.8ms +/- 4.3%     significant
    binary-trees:      13.7x as fast      112.6ms +/- 0.6%      8.2ms +/- 12.7%     significant
    fannkuch:          8.92x as fast      401.2ms +/- 0.1%     45.0ms +/- 2.0%     significant
    nbody:             4.86x as fast      210.8ms +/- 2.7%     43.4ms +/- 10.0%     significant
    nsieve:            5.16x as fast      161.0ms +/- 1.7%     31.2ms +/- 4.4%     significant

  bitops:              8.42x as fast      796.8ms +/- 0.2%     94.6ms +/- 5.3%     significant
    3bit-bits-in-byte: 26.6x as fast      154.2ms +/- 0.4%      5.8ms +/- 17.9%     significant
    bits-in-byte:      17.8x as fast      217.2ms +/- 0.5%     12.2ms +/- 8.5%     significant
    bitwise-and:       5.51x as fast      178.6ms +/- 0.9%     32.4ms +/- 4.4%     significant
    nsieve-bits:       5.58x as fast      246.8ms +/- 0.2%     44.2ms +/- 7.0%     significant

  controlflow:         28.3x as fast      113.2ms +/- 0.5%      4.0ms +/- 22.0%     significant
    recursive:         28.3x as fast      113.2ms +/- 0.5%      4.0ms +/- 22.0%     significant

  crypto:              5.29x as fast      405.0ms +/- 0.3%     76.6ms +/- 4.8%     significant
    aes:               4.97x as fast      153.2ms +/- 0.7%     30.8ms +/- 6.0%     significant
    md5:               5.27x as fast      126.6ms +/- 1.1%     24.0ms +/- 8.2%     significant
    sha1:              5.74x as fast      125.2ms +/- 0.8%     21.8ms +/- 2.6%     significant

  date:                1.07x as fast      416.2ms +/- 1.1%    389.6ms +/- 1.6%     significant
    format-tofte:      1.23x as fast      261.4ms +/- 1.3%    212.2ms +/- 2.0%     significant
    format-xparb:      *1.15x as slow*    154.8ms +/- 1.0%    177.4ms +/- 1.8%     significant

  math:                3.79x as fast      619.6ms +/- 1.1%    163.4ms +/- 5.6%     significant
    cordic:            3.24x as fast      294.2ms +/- 0.9%     90.8ms +/- 6.2%     significant
    partial-sums:      3.39x as fast      177.8ms +/- 2.9%     52.4ms +/- 11.3%     significant
    spectral-norm:     7.31x as fast      147.6ms +/- 0.5%     20.2ms +/- 2.8%     significant

  regexp:              *1.88x as slow*    305.8ms +/- 10.1%    573.6ms +/- 0.5%     significant
    dna:               *1.88x as slow*    305.8ms +/- 10.1%    573.6ms +/- 0.5%     significant

  string:              1.61x as fast     1223.8ms +/- 3.3%    760.0ms +/- 1.4%     significant
    base64:            1.81x as fast      154.8ms +/- 2.2%     85.6ms +/- 9.5%     significant
    fasta:             3.84x as fast      306.0ms +/- 2.1%     79.6ms +/- 2.6%     significant
    tagcloud:          -                  216.0ms +/- 3.5%    209.0ms +/- 1.5%
    unpack-code:       1.36x as fast      378.0ms +/- 10.1%    278.2ms +/- 2.3%     significant
    validate-input:    1.57x as fast      169.0ms +/- 2.9%    107.6ms +/- 2.4%     significant

That’s looking a bit more believable. On average Chrome/V8 seems to be twice as fast as Firefox/Spidermonkey, with results varying from 30 times faster to almost 2 times slower. It will be interesting to see how Tracemonkey compares, as it seems to be about 1.8 times faster than Spidermonkey.