5X SSR THROUGHPUT: PROFILING SSR HOT PATHS IN TANSTACK START

Summary from the TLDR Dev newsletter

TanStack Start got a 5.5x increase in throughput and a 9.9x reduction in average latency under heavy load for their SSR (server-side rendering). This was done through a repeatable process involving measuring under load, CPU profiling to identify bottlenecks, and removing entire categories of cost from the server hot path. They avoided unnecessary URL construction/parsing, eliminated client-side reactivity overhead during SSR, and implemented server-only fast paths gated by build-time constants.