One meme about Rails is that Rails can't Scale. Is it known how this meme started? Was there a particular blog post that argued this is the case?
I would say that there are real technical issues behind it. The Ruby implementation (at least ruby 1.8) is not designed for concurrency : ruby 1.8 has a global interpretor lock, and it uses green threads instead of OS native threads.
So, for a web application to scale, you have to run multiple ruby interpretors, and make them work together.
Note : I am not into web development, and It's been a long time I haven't used ruby. Maybe ruby 1.9 or JRuby don't have these issues. Maybe the global lock is not a real problem for scaling up.
Well, to scale, you need reasonable performance per line of code, right? I'm not talking C++ levels, but ... check out
for example on heapsort
But hey, Ruby is faster than vbscript!
As mentioned, there were several "hot" ror startups that suffered issues scaling. I believe that's where the issue primarily came from.
However, there's been performance issues with ruby/ror in the history prior to those meltdowns.
See: Ruby interpreter leaking memory on long running processes:
DHH's "rails myths" which documents 400 restarts per day:
And of course the infamous rails is a ghetto rant from Zed Shaw.
I'm guessing it has to do with the fact that Rails is based around the Active Record pattern, which is quick and easy to get started with, but can slide into a constant refactoring battle as your app's complexity increases. I think that's why you hear about startups in particular having troubles: they're able to get something working quickly, but as they add features, the complexity grows and that's when the trouble starts.