Doron does a great job outlining the problem and links to the fix so if you want to know more about the issue, check out his blog.

Since version 1.2 of the ArcGIS Javascript API, we’ve noticed a strange issue in both IE6 and IE7. When zooming in, memory consumption of the iexplore.exe process takes a huge jump and reaches up to 800-900 megabytes. When the operation ends, it goes back down to 50-60 megabytes. This has caused us a great deal of sorrow, as it sometimes caused our users’ systems to hang.

You can track the bug here if you wish.

Those JSAPI Bugs come right at you!

Those JSAPI Bugs come right at you!