I’ve been on a web tweaking kick lately: how to speed up your javascript, gzip files with your server, and now how to set up caching. But the reason is simple: site performance is a feature.For web sites, speed may be feature #1. Users hate waiting, we get frustrated by buffering videos and pages that pop together as images slowly load. It’s a jarring (aka bad) user experience. Time invested in site optimization is well worth it, so let’s dive in.What is Caching?Caching is a great example of the ubiquitous time-space tradeoff in programming. You can save time by using sp...