Ruby is by far my personal favorite language its incredibly elegant and the speed differences between it and other scripting languages i.e. PHP, Python, Perl and Bash is fairly small. Whats more is these speed differences will differ depending on what your doing. If you test how quickly it will update 1000 strings one will be faster than the others however if you test how quickly it can parse a JSON object you might get completely different results. Also keep in mind good hardware is becoming cheap so you can run a fairly intense app on as little as $20 a month with any of these languages and move up as you need. So speed isn't really an issue. All of the scripting languages are at least in the same league as far as speed go.
Real speed in a web app comes from many factors, the network your server is on, your server hardware and configuration of the database and web server application to name a few. As far as your code goes real speed comes from many factors as well, how efficiently you hit your database, your design and archetecture etc...
Hope that helps. I guess to surmise go were you feel comfortable and happy coding. Also like jamesw said Ryan Bates Rails casts is a great resource. If you end up going with ruby I would also recommend http://rubykoans.com/.
Last edited by tyger86 (2012-12-09 02:32:35)