Just because it is written in D doesn't automatically make it fast. If you were to run that program on an underpowered host with a database system that has to c

Just because it is written in D doesn't automatically make it fast. If you were to run that program on an underpowered host with a database system that has to constantly swap, with not enough CPU time available it would be slow too. And that is the bigger problem, people are running their websites on underpowered hardware in the first place. The limit should be the network connection, not the page rendering time... but unfortunately that isn't always the case.