It's about the people who are hosting the Pi website, and what they did to manage the burst of activity when the Pi Zero was announced.
Right, but the title strongly implies that the article is talking about executing PHP on the Pi.
I had the same reaction, I was hoping to hear about a problem solved by the Pi Zero, maybe configuration tweaks or something for PHP, it sounded almost like it was going to give a performance tip as far as the Pi Zero is concerned.
A great example of how a headline can tie barely related content into the latest trend / top-rated HN article to catch a few more page views / front-page votes... marketing!