Mono's ASP.NET or MVC or Manos are all running natively compiled code, so for equivalent tasks they should all be faster than interpreted languages.

Whether this matters or not will depend on the what your application is doing and how many users you have. For example, if your application is database bound or file system bound you wont likely notice much of a difference as the time you spend running CIL code or interpreted code is a small portion of your overall CPU consumption.

With Mono 2.8 we significantly improved Mono's web server scalability, but this will not matter if your application does not use or require more than a handful of CPUs. But is incredibly useful for people that are scaling servers under load.

Miguel,

How is your team keeping such a fast pace? Do you get a lot of assistance or documentation for Microsoft. Your rate of feature parity with the MS releases is impressive.

Well, we prioritize what developers need using our Moma tool (this tool does a static analysis of your executables and libraries and informs us what APIs are the most important to get).

In addition, a big help was the fact that Microsoft open sourced large swats of code in this release (DLR, MWF, OData, LINQ, and a bunch more).

I haven't done any benchmarking and I don't use RoR or PHP much, but as a data point, the Mono stuff running under Apache seems slower than similar Java code running under Tomcat.