I like Matt Holt and Caddy. My feedback here is that it would be useful to do profiling in a language-agnostic way so that other servers can participate and publish results! In general I think what users want to see is a timeseries of mem/cpu usage given an easy-to-characterize workload. The workload could be something like 'traffic hits a noop GET endpoint and who's rate doubles every 5 seconds'. Plenty of tools exist to do this kind of testing (e.g. ab for generating traffic, htop for measuring resource load; I'm sure many other options exist on linux).

It's tempting to use language specific profilers because they give you so much "for free" - they are particularly useful for the devs of the server itself, since they give great insight into the inner workings, can help identify bottlenecks. But in a world where everyone is comparison shopping, black box, language agnostic profiling would be more useful to consumers. Heck you might even go in with other server vendors to build something! A nice opportunity for collaboration!