APC is short for Alternative PHP Cache. It is an Open Source opcode (operation code) caching system for PHP.
When using APC (or any good, well configured, opcode caching system), PHP based applications are able to operate faster, because, rather than being parsed and compiled, your PHP script operations are cached in APC, and delivered upon request from there, cutting out some steps where functions are consumed, taking time.
This PHP ode still needs to be executed (order PHP Script -> Parse -> Compile -> Execute -> Output… APC removes the Parse and Compile steps).
Alternative to what?
So we know its called Alternative PHP Cache, right?! But what is it the alternative, well, too?!
Zend. That’s what.
Memcached, which is an object cache (storing DB objects in memory) and is really beneficial in multi-server environments.
Varnish – which is a reverse HTTP proxy, and basically stores whole pages, ready to blast out all compiled and whatnot.
And, since you’re here, reading about APC, you’re probably thinking about squeezing speed out of your setup, so also have a look at Nginx, and PHP-FPM for good measure.
In a WordPress and WooCommerce context, you could do a lot worse than looking at making sure your setup is at least PHP 7.0 or higher, as well as toggling all of the above to make things faster than lightning. Or just ask us to optimize your site for you! Get in touch here.