Python and Ruby are fine languages. Miles ahead of most others. They work well in many situations.
Remember their most common implementations are relatively simple. Don't use them as the benchmark of where the performance can really go, and has been for some time, e.g. in Smalltalk, Common Lisp, and Scheme where more attention has been paid to efficient implementations.
Microsoft will be missing a huge opportunity if they settle for current Python and Ruby performance as their "scripting" language par. The first step toward this new consciousness would be to stop using the term "scripting". Call them "dynamic" or "agile" or something that does not connote just slow "glue".