Chirpy is an open source Visual Studio Add In For Handling JavaScript, Css, DotLess, and T4 Files.

Better Page Performance
When you validate your site against YSlow it gives you reports on why your webpages may take some time to render in the browser – Chirpy can help with this big time by minifying script files like javascript, css and more so that there are less requests made to the server on each page request – better page performance is always good.

YSlow

The full list of what Chirpy can do can be found here.