neXpert - YSlow clone for Fiddler

neXpert is a add-on to Fiddler similar to the YSlow add-on that integrates with Firebug on Firefox. The version 1.0 released recently still has some rough edges but looks to be a good addition to any ASP.NET Developer's toolkit.

neXpert looks for performance issues and generates a HTML report with recommendations based on it's findings. Some recommendations include -

• Be aware that IIS is case-sensitive and changing the case (Upper, lower, Title) for an object requested is considered a new request.
• ..the best practice is that the size of the ASP.NET View State does not exceed 30% of the total page size.
• The ETag header is used for validation of objects in a user's cache. There have been many issues with the implementation of ETags in both web servers and web clients. The current performance best practice is to verify the correct configuration of ETags if the(y) are necessary and to turn them off if not.

But as Jeff Atwood says about YSlow -

There is no such thing as one-size-fits-all guidance. Strive to understand the advice first, then implement the advice that makes sense for your specific situation.