During my investigation of our ASP.NET application performance issue, I've found out that XmlSerializer may require a long warm-up. The first time, when it's used for a specific class (de-)serialization, can take up to 500 ms om my machine!
We use a lot of web crawling to get data from third-party websites. Some crawling is not as easy as just a simple GET request, so we have to send specific POST data, cookies and HTTP headers. And all this needs to be debugged. Fiddler2 is the gold standard for web debugging tools, so I'd like to use it in this case too.