Browser Cache Usage - Exposed!
The Yahoo User Interface Blog did an interesting study of how useful browser caching really is. When the Yahoo page is cached, load time drops from 2.4 seconds to just 0.9 seconds. But before you spend time optimizing your web pages for maximum caching, it turns out roughly half the users won't see any gain. And there's a significant number of users with caching permanently disabled. Here's a nice chart of their results: