The jQuery team recently released version 1.4 of their widely popular JavaScript library. This release includes significant performance improvements.
Many of the most popular and commonly used jQuery methods have seen a significant rewrite in jQuery 1.4. When analyzing the code base we found that we were able to make some significant performance gains by comparing jQuery against itself: Seeing how many internal function calls were being made and to work to reduce the complexity of the code base.
jQuery 1.4 addressed 207 bugs vs. 97 bugs in the 1.3 release. It also supports the following browsers 100%: Safari 3.2, Safari 4, Firefox 2, Firefox 3, Firefox 3.5, IE 6, IE 7, IE 8, Opera 10.10, and Chrome.
Ensure that you read through the list of potentially-breaking changes to be aware of what might cause problems in your applications.