I was on the team that built news.com.au, which, along with the other news sites we set up in a multi tenant WordPress setup, was at the time the largest commer

I was on the team that built news.com.au, which, along with the other news sites we set up in a multi tenant WordPress setup, was at the time the largest commerical WordPress site in the world, getting something like 500 million monthly page views. We made extensive use of caching to say the least.