Google Analytics has released an asynchronous version of their tracking code. Listed among the benefits of using the asynchronous tracking code are shorter page load times and more accurate visitor tracking–both good reasons to consider using the asynchronous code.
Implementing the asynchronous code is as easy as implementing the current, synchronous version. If, however, you have made any customizations to your existing tracking code, you will need to migrate those customizations to the asynchronous version. Those interested in migrating GA tracking code customizations should take a look at Google Analytics for Developers and these migration examples.