How Etsy Reduced Page Load Time to 0ms
Etsy shipped a performance improvement so dramatic that 40% of their users now see product pages load in essentially zero milliseconds. No infrastructure overhaul. No rewrite. Just a clever use of browser prediction and a 15-line JSON config.
If you’re thinking “prefetching is old news,” I’ve got news: you haven’t seen the Speculation Rules API yet.
The 200ms Window
The traditional web flow is brutally wasteful. User hovers over a product link. User’s brain decides this looks interesting. User moves cursor to click. Click event fires. Browser initiates request. DNS lookup. TCP handshake. TLS negotiation. HTTP request. Server processing. Response headers. HTML starts streaming. Parser kicks in. More requests for CSS, JavaScript, images.
The entire time between hover and click—typically 200-500ms—the browser just sits there. Your user has already made their decision. The machine is waiting for permission.
This is the opportunity Etsy exploited.
