Joel of Joel on Software fame has bashed Ruby performance on his blog. The outcry caused by this flamebait has been large as expected. Yet, out of the gut (without any benchmarks to back up my feelings) I thought he was probably right that Ruby is small.
However, I found an interesting comment on the Smallthought blog: the author points out that Ruby's performance is slowed down by a naive implementation of the interpreter and points to a Smalltalk interpreter just OSSed by Sun. Now, if we combine this and Sun hiring the JRuny guys there is cause for hope to get a better Ruby interpreter in a short while.