Newbie Level Optimization Technique:
1. Themes Optimization – Find the fastest themes out there, do a pingdom tools speed test at http://tools.pingdom.com/ and only go for the minimal theme installation for the best optimum speed possible.
2. Plugins Optimization – Find the fastest plugins out there, refer to 1 on speed test.
Intermediate Level Optimization Technique:
1. Install Caching Plugins – Experience says that W3Total is the most “compatible plugin” with major WordPress versions. There have been successful cases with the installation of SuperCache plugin and also plugins like BatCache. Depending on the hardware and setup used, each caching plugins have their pros and cons. You have to deploy your caching plugins in accordance to the kind of site you are running.
2. Install Opcode Caching – For PHP5.5 versions and below, installing an opcode caching system such as apc helps speed up WordPress by a factor of 2x at least.
Expert Level Optimization Technique:
(message is vague if you are not an expert, and only experts can understand the lingo mentioned.)
1. Caching Plugins Fine-tuning – Improving (or hacking) LiteCache or HyperCache plugins is one of the ways to get it to run them as they are the most basic core fundamental plugins for WordPress, the effect is much better as the overhead is much lower.
2. Debug PHP runtime slowdowns – Often, unnecessary function calls can be “bundled” together or removed totally. Identify where the problems are and fix them.