Opcache is one of PHP's most powerful tools when it comes to performance. With the release of PHP 7 it received a new feature which has gone largely un-noticed: the file cache. Depending on your hosting environment and/or traffic levels the file cache may be able to help squeeze even more performance out of PHP.
PHP apps can easily begin to slow down over time as they grow, and with the recent patches for the Meltdown vulnerability adding a performance penalty to many workloads this slowdown can be amplified. Often there are some simple changes that can be made in order to see a measurable performance improvement for production workloads.
Recently I've been trying to make some improvements to sites that I'm ivolved with, particularly converting images to SVG format and implementing HTTP Content Security Policy (more to come on those later). While doing so I ran into a strange issue to do with how Microsoft Edge handles the combination of these two technologies which only seems to be documented in an Edge bug report.