Not a great metric. My blog once got unexpectedly slash dotted (ended up on Reddit and HN front pages for a day; silly enough the post was the one I put the least work into by far and the idea was not even mine). I was at the time running WordPress with WP Supercache using only right PHP workers. The site never had a hiccup. Ergo PHP is the best language out there? :)

In reality, do use something like WP Supercache. It will save your hide.