Amazon and others have demonstrated the strong link between performance and user activity: as the wait for pages goes down, the amount of time and money the user spends goes up.
In a Net Magazine interview, BBC dev Jamie Knight indicated how they made performance changes to the BBC website, driven in part be a user comment. The key was to speed up the site (of course), but to also allow for the best possible user flow from page to page, something which direly important in Jamie's book.
Performance is about more than just how long it takes for a page to load — to preserve our users’ flow we need to consider the overall experience and where the pauses lie;
One of the areas that the BBC chose to explore and aggressively tackle is caching. The goal was to have the highest cache hit rate as possible, and did so employing a number of tactics.
You can read the article which was published online here.