PHP 7 review: sources of performance improvements (from PHP core developer)

PHP 7 introduced new features: scalar type declarations and return type declarations. In this post we will show how these features makes the maintenance of large pieces of code significantly easier by multiple developers and writing more robust tests. For the owner of the large PHP-based application it means more quality with less money spent in a long-term perspective.
Tumblr has upgraded its servers and web app’s code from PHP 5 to PHP 7. Almost immediately Tumblr’ developers saw the latency drop by half, and the CPU load on the servers decrease by at least 50%. Badoo freed up around 300 servers ($100,000 a year in hosting cost savings) and got a visual performance boost at the same time (overall response time improved by about 40%)!