Edge runtime cost realities: Vercel Edge vs serverless
Edge runtime wins on latency and cold-start, loses on cold cache and invocation cost at high traffic. The crossover point sneaks up on you.
Edge runtime is genuinely faster, global TTFB, no cold starts, geographic affinity. The marketing isn't wrong. The pricing is also not wrong; it just isn't what most teams think.
At low traffic, Edge is cheaper than Lambda or Vercel serverless. The crossover happens around mid-six-figure invocations per month, where Edge's per-request pricing starts beating cold-start-discounted serverless. After that, Edge is more expensive, sometimes 2-3x.
The sane default I land on: Edge for the route shell (auth, rewrites, A/B variants) and serverless for the data-heavy work. That keeps TTFB low for the LCP-critical path while keeping invocation cost under control on the long tail. Pure-Edge architectures look great on slides and surprise you on the bill.