PHP 7 moves full speed ahead
Spoiler: it's all about performance. Coming to a host near you in 2015.
http://www.infoworld.com/article/2841561/php/php-7-moves-full-speed-ahead.html
Posts tagged with performance
Best Practices for Using the Vary Header
Vary is one of the most powerful HTTP response headers. Used correctly, it can do wonderful things. Unfortunately, this header is frequently used incorrectly, which can lead to abysmal hit ratios. Worse still, if it's not used when it should be, the wrong content could be delivered.http://www.fastly.com/blog/best-practices-for-using-the-vary-header/
