We did it! Hundreds of our application servers are now running on PHP7 and doing just fine. By all accounts, ours is only the second project of this scale (after Etsy) to switch to PHP7. During the process of switching over we found a couple bugs in the PHP7 bytecode cache system, but thankfully it’s all fixed now. Now we’re excited to share our good news with the whole PHP community: PHP7 is completely ready for production, stable, significantly reduces memory consumption, and improves performance dramatically.
In this article, we’ll discuss the process of switching over to PHP7 in detail, explaining what difficulties we encountered, how we dealt with them, and what the final results were. But first let’s step back a bit and look at some of the broader issues...
https://techblog.badoo.com/blog/2016/03/14/how-badoo-saved-one-million-dollars-switching-to-php7