Performance and optimization · Paying for a request

Network performance-style app

Illustrative system design for a paying for a request app like Network performance: 4 topics to read, from requirements to deep dives.

Illustrative design, not Network performance’s actual implementation. Arrowbox is not affiliated with Network performance’s owner. Disclaimer

Core

Where a request's time goesBeginner · 35 min read · Sign in to read
A request spends its time on DNS, a TCP handshake, TLS, waiting for the first byte and downloading; on mobile, round trips rather than bandwidth dominate, so reusing connections matters more than shrinking files.
HTTP caching in the browserIntermediate · 30 min read · Sign in to read
Cache-Control decides how long a response is fresh; validators (ETag, Last-Modified) let a stale copy be revalidated with a cheap 304; fingerprinted file names make static assets cacheable for a year.
Caching with a service workerAdvanced · 35 min read · Sign in to read
A service worker sits between the page and the network and chooses, per request, cache-first, network-first or stale-while-revalidate; its install, waiting and activate lifecycle decides when a new version takes over.
Fewer, smaller requestsIntermediate · 32 min read · Sign in to read
Compress text responses, ask only for the fields, hours and page sizes the screen draws, and combine small requests when that saves more than it delays.