Brian Fioca from ONLamp.com posts an interesting articleregarding the scaleability and performance of PHP vs. Java. Inresearching his article he talked at length with "Owen Byrne, cofounderand Senior Software Engineer at digg.com" to learn how he addressed any problems they encountered during their meteoric growth.
Byrneasserts that "none of the scaling challenges we faced had anything todo with PHP," and that "the biggest issues faced were databaserelated." The article also makes some simple recommendations on Apachetuning and MySQL database configuration strategies to address commonproblems.
Fioca concludes with the following assertion:
It turns out that it really is fast and cheap to develop applications in PHP. Most scaling and performance challenges are almost always related to the data layer, and are common across all language platforms. Even as a self-proclaimed PHP evangelist, I was very startled to find out that all of the theories I was subscribing to were true. There is simply no truth to the idea that Java is better than scripting languages at writing scalable web applications. I won’t go as far as to say that PHP is better than Java, because it is never that simple. However it just isn’t true to say that PHP doesn’t scale.