This extensions adds APCU / APC support to your opencart caching system with failback file storage support.
If your server does not have installed the APCU / APC, then it simply optimizes the file storage caching system!

Also VQMOD file adds support for NGINX / VARNISH.
It adds the right headers to tell the NGINX / VARNISH when to cache or not.
It build for ENGINTRON cPanel extension, probably will work with any other extension.

When "tells" the NGINX / VARNISH not to cache:
1) User is logged
2) Guest has added a product to the cart

Source: https://github.com/zstergios/Opencart-1.5-APCU-CACHING