What is OPCache?
Since WP Rocket 2.7, you might have seen a new option in the admin bar to Purge OPCache, if your server has PHP 5.5 or higher.
If you're wondering what is this option about, here is what you can read on the PHP manual for it:
OPCache improves PHP performance by storing precompiled script bytecode in shared memory, thereby removing the need for PHP to load and parse scripts on each request.
In other words, a PHP script when it is executed, is compiled into opcode, code that is understandable by the machine. OPCache stores this code into memory on the first execution, to be reused afterwards, thus leading to performance boosts.
OPCache replaces APC, and is an alternative to XCache, as a PHP accelerator.
WP Rocket enables you to reset the OPCache content easily if needed right from your WordPress admin bar.