The Tideways.io blog has posted a set of four macro-optimizations you can do to help improve the overall performance of your application. Note the "macro" here, not "micro", so these are larger, more platform-level changes.

This blog post describes four macro-optimizations for PHP applications that are essential to consider before investigating other possible optimizations. [...] While its fun chasing after small micro optimizations, often it is debatable if the developer time is well spent. After all I/O is the more important bottleneck in almost every application. [...] But its much more efficient to fix the big issues first. The changes I present in this post can be done quickly and their gains can be massive.

The four suggestions he makes cover different areas of a standard application:

• Upgrade PHP to a recent version
• Use accelerator such as APC or OPCache
• Close Session for Writes
• Don't run XDebug in Production

Each tip comes with a bit of background on why it's a good idea and some have links to other resources supporting the change or update proposed.