I'm not on the HPHP team, but when discussing these results internally, they mentioned that HPHPc performance was improving during this time as well (as you wou

I'm not on the HPHP team, but when discussing these results internally, they mentioned that HPHPc performance was improving during this time as well (as you would expect we would need to keep running the site efficiently), and the graph showed point-in-time comparisons of their performance, not from a baseline. As to whether it would have been possible to get better performance on HPHPc, I'll let people with more knowledge answer. The benefit of having a single runtime for development and production (and production-like staging environments) is huge, though. There may also be benefits in the push process, which while fast when compared to most other companies, which will continue to deliver benefits for increased speed.