The story
Rosa’s farm-box delivery does eighty percent of its orders between five and eight pm, the same three hours her site used to be slowest. Hungry customers browsing forty products at once is a database stress test scheduled daily.
The complication is stock: six bunches of asparagus means six, and a cached “in stock” lie ruins dinner and trust together. So Rosa never cached anything, and the dinner rush stayed slow for years.
The real answer splits the page: the catalogue serves as cached HTML while stock levels stay live through the object cache and excluded fragments. Browsing is instant, the asparagus count is honest, and five-to-eight is now just the busy part of the day.