Kensai7 writes "Recently, Facebook provided us with some information on their server park. They use about 30,000 servers, and not surprisingly, most of them are running PHP code to generate pages full of social info for their users. As they only say that 'the bulk' is running PHP, let's assume this to be 25,000 of the 30,000. If C++ would have been used instead of PHP, then 22,500 servers could be powered down (assuming a conservative ratio of 10 for the efficiency of C++ versus PHP code), or a reduction of 49,000 tons of CO2 per year. Of course, it is a bit unfair to isolate Facebook here. Their servers are only a tiny fraction of computers deployed world-wide that are interpreting PHP code."