Should I use haml or erb or erubis for potentially high traffic site?

I have been playing with Haml recently and really like the way the resulting code looks to me...the developer. I'm also not too worried about a designer being able to consume or change it...we're a small team.

That said, beginning work on a project we believe will generate quite a bit of traffic (who doesn't?). I'm concerned that there are things I just don't know about haml. Is there anything erb can do that haml can't? Does haml have a negative effect as a project grows? Are there other things that should be considered?

And finally...how does Haml compare speedwise to erubis? I see that it supposedly beats erb and eruby now...

Thanks!

Haml rocks. I haven't seen any recent performance numbers but it is pretty close to erb these days. I think that it might be faster than erb if you turn on ugly mode (which prevents the pretty indentation) We're doing 2.8 million pageviews a day with Haml.

There is a benchmarker checked into the Haml source tree: http://github.com/nex3/haml/tree/master/test

Update November 2009

Nathan (Haml's main developer) published some Haml 2.2 benchmarks on his blog. You can see the exact numbers there but in short:

• Normal (pretty printing) mode = 2.8 times slower than ERB
• Ugly mode (no pretty tabs added) = equal to ERB

You can enable ugly mode by placing Haml::Template::options[:ugly] = true in an initializer or environment file. Note that ugly mode isn't really that ugly - the resulting HTML is actually much prettier than ERB - it's just not indented nicely.

If you use Rails, the performance difference between Haml and erubis is negligible: templates get compiled and cached after the first hit, anyway. Combine this with fragment and page caching and you can rest assured that views are not the performance bottleneck of your application.

The question you should be asking yourself is: do you like writing Haml? Does it make you more productive? Then you can decide easier.