ServerTimingHeader
ServerTimingHeader refers to the HTTP response header used to expose server-side timing information to a client. It is designed to help developers understand how time is spent during request handling by reporting the durations of different server components, such as application logic, database queries, or caching layers. When present, the header allows performance data to be observed alongside other network metrics without requiring additional client-side instrumentation.
The header value is a comma-separated list of metric tokens. Each token starts with a metric name
In practice, servers instrument components and attach one or more tokens to the Server-Timing header to convey
Security and privacy considerations should be taken into account, since exposing internal timings can reveal implementation
See also: performance instrumentation, HTTP headers, browser developer tools, profiling.