[yesimahuman]

I've never heard anyone say Java is slow when compared with Ruby or Python. In fact I'm looking at some benchmarks that show the complete opposite. And as for PHP, Facebook is a completely different company with traffic very few startups will ever see.

I also don't think the argument that Java or C# is somehow a worse fit for agile development is valid. Sure, I might be able to get my app out more quickly with Python or Ruby, but long term it's not like I'm adding thousands of lines of code a week. A startup takes a long time to build, if you are still writing a ton of code half a year out and you aren't making revenue, I think you should take a step back from coding and focus on business development.

I think agile development is hindered or bolstered by your tools (using git instead of svn, for example) more than the language you write your program in.