When you’re working through a backlog—opening an issue, jumping to a linked thread, then back to the list—latency isn’t just a metric. It’s a context switch. Even small delays add up, and they hit hardest at the exact moments developers are trying to stay in flow. It’s not that GitHub Issues was “slow” in isolation; it’s that too many navigations still paid the cost of redundant data fetching, breaking flow again and again. Earlier this year, we set out to fix that—not by chasing marginal backend wins, but by changing how issue pages load end-to-end. Our approach was to shift work to the client and optimize perceived latency: render instantly from locally available data, then revalidate in the background. To make that work, we built a client-side caching layer backed by IndexedDB, added a preheating strategy to improve cache hit rates without spamming requests, and introduced a service worker so cached data remains usable even on hard navigations.…