IE6 in slow browser shocker!

Ok, so it’s not that much of a shocker… We all know that IE6 is slow. But how slow, really, in comparison to the modern browsers?

IE6 is 2 orders of magnitude slower when comparing pure JavaScript execution speed with Google Chrome (version 9).

What’s also interesting is that IE7 is barely better than IE6 (1.4 times the speed) and IE8 doesn’t set the world on fire either (5.5 times the speed). Only the unreleased IE9 gets anywhere near the same ballpark as its rivals:

JavaScript performance (SunSpider 9 tests) - Caplin Systems Ltd.

What does this mean for trading applications?

Performance, display latency and user-interaction correctness have always been a concern for trading applications, whatever the front-end technology. You need to get the prices you want delivered to the screen as quickly as possible, yet in an efficient manner, and ensure that users get executed reliably at the price they saw and clicked on the screen. This requires optimised data processing, display scheduling and input handling. All of which can be a particular challenge in a slower single-threaded environment.

In practice, this means that applications developed mainly in Firefox, Safari or Chrome are unlikely to perform acceptably in IE6 or 7, even when tuned with these concerns in mind. The corollary of this is that applications developed to work well on the older Microsoft browsers are likely to run exceptionally fast in newer browsers (and we’re seeing this at Caplin with our Caplin Trader framework)

It’s important to remember that the now ancient IE6 (coming up to its 10th birthday in August this year) and IE7, though dwindling fast, are here to stay for some time longer in the banks. The HTML5 explosion has caught everyone’s eye, but if your application doesn’t degrade gracefully and perform acceptably on the older browsers then you won’t last long on the desktop of your target users.


  • Browser performance is more than just JavaScript execution speed. Visual element manipulation (DOM elements and CSS) comes in to it too. But the old MS browsers are notoriously slow at this too.
  • These performance figures were NOT all tested on the same machine (ever tried installing IE6, 7, 8 and 9 on the same computer?!), but were run on similar hardware and normalised based on results from the other browsers.
  • SunSpider is just one measure of JS performance, but other tests show similar differences

One Response

  1. […] are better off written in the native language. However the latest browsers run JavaScript orders of magnitude faster than the Internet Explorer 6 days. In addition new HTML5 features such as ‘web workers’ will […]

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