After enabling OPcache for PHP7 in FPM/FastCGI mode, this tool is rather nice for monitoring the results: https://github.com/amnuts/opcache-gui
(100% usage and 100% hit rate is generally good, it means you’ve allocated enough memory to cache the precompiled script bytecode without wasting a lot of memory by overallocating the cache size.)
PHP7 is significantly faster than some of the maligned earlier versions, see this benchmark article extract:
PHP is not dead, both the platform and infrastructure continue to evolve, and indeed to support a large percentage of the internet. On the language side a lot has been done to complete the object oriented feature set. Though with a long history, there’s a lot of PHP code in existing that wouldn’t meet a lot of coding standards.
In this benchmark PHP7 came out 10x faster than PHP5.6 Your Mileage May Vary.