[ryah]

Web site performance problems usually don't have much to do with the raw executing speed of the language they're written in. The problems derive from poor understanding of how to handle concurrent connections. If your app is written in C, but is accessed through a CGI interface - starting a process for each request - then it's going to be slow. Similarly if you write a web server which makes blocking connections to a backend database, your server will be slow. If you use threads to handle concurrent connections, you're going to allocate 2mb stacks for each user - and your website is going to suck. This all has little to do with how fast a language can invert a matrix.

[warfangle]

And then there's situations like porting a Rails app to Lift and seeing a huge improvement in performance without touching the database / storage IO: http://lambda-the-ultimate.org/node/2147

Granted, it's not from the most unbiased source, so take it with a grain ;)

[ryah]

That has to do a lot with Ruby's awful thread implementation. You could possibly port the app again to Ruby EventMachine and see even better performance.

The point is - for 99% of people it's not the language, it's the I/O