If you have recently searched for WordPress speed and performance optimization tips and techniques, you have definitely seen several things being recommended all the time: different caching mechanisms (full page caching plugins, memcached, reverse proxies), sprites, CSS & JS minification, to name a few. All of them are indeed viable and really effective ways to speed up your site performance. However, they may not be equally applicable for everyone and there are cases in which they can actually break your website. This presentation covers what actually can go wrong with each of the most popular and widely accepted performance optimization techniques, how to implement them without breaking your site and how to fix the most common issues with different speed boosters.