Joel Spolsky writes again about how Ruby performs poorly, but his posting reveals a fairly fundamental misunderstanding of both the language and its community, IMO. He seems to assume that Ruby proponents claim that the language is good for every computing problem, but of course nobody in their right mind would ever claim such a thing about any language. I had the opportunity to sit beside Matz, the creator of Ruby, at a speakers' dinner at JAOO a few years back, and I found him to be not only very pleasant, but also incredibly humble. He would never argue that Ruby can do it all.
As I wrote in my previous blog entry, extending Ruby is pretty straightforward. The examples Spolsky gives of Ruby being too slow could all be handled via extensions relatively easily. As the old adage goes, use the right tool for the job.
I was going to write more, but DHH nails it.