Ruby has a fairly well deserved reputation as a slow language. I tend to think that for its most relevant use cases (running high level programs like text editors and web sites, etc) it doesn’t much matter. You could always write your application in C or Java, but who wants to do that if they can help it?
Is Ruby really faster though? Not really. It’s really effectively the same as these other languages. Check out this graph for some perspective:
see source: http://shootout.alioth.debian.org/u32/which-programming-languages-are-fastest.php
I don’t consider this an indictment of Ruby. Actually, I see it as a great reason to use it. If I can get the same performance out of Ruby as Python, PHP, or Perl then I am certainly not going to choose Perl. As for Python or PHP, I think the choice is a matter of taste. I personally like the elegant readability of Ruby. It is written more for my brain than for a CPU. And it’s not any slower than the more C-like Python and it’s proven itself much more malleable than PHP. Good stuff.
And as for Rails? I don’t think its performance is anything to worry about either: