IE 7 vs IE 6

Back in April I wrote an entry complaining about IE’s performance as a Web 2.0 platform:

“From a Web 2.0 application developers perspective (developers who use a lot of JavaScript and DOM manipulation), IE 6 is plagued by a number of well known problems such as its ability to readily leak memory. Regrettably, Microsoft’s next release of Internet Explorer, IE 7, does little to resolve these issues.”

I am happy to say that I was wrong.

Microsoft’s IE team has clearly been hard at work on improving their browser’s memory management and JavaScript performance. IE 7 has made some significant leaps forward based on some initial in house testing here at Zimbra. We are in general observing about a 2x performance improvement with IE 7 vs IE 6 when using the Zimbra Web Client (ZWC).

As is well documented, IE 6 is notoriously bad at leaking memory, particularly due to circular references that include COM objects. The good news is that our tests indicate that this problem has been solved in IE 7. While in our test profile, it appears to consume more memory than Firefox, IE 7 seems to have solved the horrendous memory leaks exhibited in IE 6.

We also looked at the performance of Firefox, IE 6, and IE 7 over a set of common ZWC operations such as logging in, viewing messages, navigating around various folders, viewing contacts, and performing various calendar operations. The graph below shows the relative performance of each browser against the other:

Again we see that across just about every operation, IE 7 performs better than IE 6; however, for the most part Firefox still beats out IE 7. When we looked at the sum total time it takes for all operations to be performed (admittedly a coarse grained metric), we noticed that IE 7 was about twice as fast as IE 6; however, Firefox was more than twice as fast as IE 7 and about four times faster than IE 6.

In conclusion, IE 7 has made some quite significant improvements over IE 6, both in terms of performance and memory management; however, there is still room to improve – particularly against Firefox, a challenge I hope the IE team will be taking up.