The Path of a Request — Tech Epitome

The Path of a Request — Tech Epitome

Before your code runs

By the time a request handler executes, several round trips have already happened. Counting them is the cheapest performance work available, because each one is a fixed cost you pay regardless of how fast your code is.

DNS resolution: turn a name into an address. Cached aggressively, but a cold lookup can cost tens of milliseconds.
TCP handshake: one round trip to establish the connection.
TLS handshake: one or two more, depending on version and whether the session resumes.
The request itself: one more round trip before the first response byte.

Four places to intervene

Everything in this section is one of four moves, and it is worth being able to name which one you are making.

Move	What it does	Best for
Get closer	Serve from a location near the user	Static assets, cacheable reads
Reuse the connection	Avoid repeating handshakes	Chatty clients, service-to-service
Send less	Compress, paginate, trim fields	Large payloads on slow links
Send less often	Batch, coalesce, cache client-side	High-frequency small calls

Nearly every network optimisation is one of these four.