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Comparing Browser JavaScript Performance

Posted by ryuzaki0 on from the lining-'em-up dept.

Thwomp writes "Over at Coding Horror Jeff Atwood has an interesting writeup on JavaScript performance in the big four browsers. He used WebKit's newly announced SunSpider to produce the results. If a probable anomaly in the IE7 results is overlooked, Firefox 2 is the slowest of the bunch. Atwood has also benchmarked the latest Firefox Beta, and its performance seems to be improved significantly."

4 of 134 comments (clear)

  1. A grain of salt by pwnies · · Score: 5, Interesting

    Take note of the tests for the latest Firefox beta though, notice that he's using a different system with .2Ghz more and he's on a 64 bit system versus a 32 bit. Although it's not a huge leap, it IS a difference. Different system different benchmark.

  2. Vista + ie7 took hours! by mseidl · · Score: 5, Funny

    <html>
    <body>
    <script type="text/javascript">
    var i=0
    for (i=0;i<=10;i++)
    {
    document.write.UAC("Cancel or Allow?");
    document.prompt("Yes, No, Maybe?);
    }
    </script>
    </table>
    </body>
    </html>
  3. Bah humbug! by SirJorgelOfBorgel · · Score: 5, Informative

    What an absolutely horrible speed test.

    First off IE6 is not tested, while it is still the most used browser. Also Opera 9.5 is not ready, it has so many bugs it just isn't funny anymore. Many sites break that worked fine in Opera 9.2.

    But let's get to the good stuff. Yes in pure JavaScript like this, IE might be faster than Firefox. But in real world situations it clearly isn't. There is no test done on layout manipulation (and such) using JavaScript. Internet Explorer is notoriously horrible at this, especially if you use it combination with PNG's with alphachannel or complex CSS. Not to mention if you have to use JavaScript hacks because of IE6's lack of CSS support for the simplest things.

    Funny is also how almost all JavaScript library speed tests I've seen put Internet Explorer far behind the others.

    In 'real world' JavaScript performance Opera and Safari would be the winners, where I'd choose Safari as absolute winner, as Opera gains a lot of redrawing speed by cutting corners it should not cut which often result in display corruption (ie, the type that goes away when you force a redraw by minimizing and then maximizing the window again, or moving another window over Opera and then away again). Quite a bit behind in speed after Safari and Opera would be Firefox, followed even further back by Internet Explorer.

    As a developer I still prefer Firefox for development though. Webkit is awesome, but the Safari GUI just plain sucks. Opera... hmm, I like it on my mobile devices, but it's just too weird for the desktop (what, textarea's don't even support scrolltop? wth!)

  4. Re:Hmmm by mulveling · · Score: 5, Informative

    I've done some work before that required concatenating very large strings in Javascript, and the code was certain to be run in IE by our users. It was clear to me from the observed performance, that when you use the "+" or "+=" operators to build a large string from many smaller strings, IE does not attempt to optimize things under the hood with a String Buffer. In fact, *every* "+/+=" operation seems to allocate an entirely new String object to contain the result. Problem is, most of those Strings are intermediate results that will just end up get tossed by the garbage collector, and hence their allocation was for naught. A quick analysis of this means that we're looking at a total memory allocation cost on the order of N*N, which leads to very unreasonable performance when you're looking at concatenating 1000+ strings. From scanning the SunSpider string benchmarks, it looks like the specific benchmarks that IE has trouble with are indeed using the +/+= ops to build big Strings.

    Fortunately, there are workarounds. The easiest is put all the component strings you wish to add together into an array and then call join('') on the array to build the result string. This executes much, much faster in IE and should be fast in the other browsers as well. Before I figured out the join('') "trick", I implemented a scheme to add the component strings in a much more optimal order...the N^2 cost is only if you add them in a naive, left-to-right manner. By pairing up adjacent components and adding, you get N/2 intermediate results. Repeating the pairing process on these intermediates, and over again until you have your 1 final result, the allocation cost is only N*Log(N), which is far FAR better than N*N. Incidentally, this is similar to the "Russian Peasant Algorithm" technique used to optimize the addition of N numbers on massively parallel processors...whereby you can reduce the cost of N additions from N to Log(N) time assuming there are enough processors (N/2) on hand. When I learned about the join(), I compared its performance to the Russian Peasant technique and got very comparable results in IE. Weired, since if join() were using a StringBuffer under the hood (like it should), then its performance should be O(N), not N*Log(N)...

    Anyways, in summary - yeah it sucks hard that IE does that, but it's easy to workaround once you know what's up (gee, that's true in so many cases with IE quirks).