Network Timing breakdown phases explained

Network timing breakdown phases.png Here's more information about each of the phases you may see in the Timing tab: - Queueing: The browser queues requests when: - There a higher priority requests - There are already six TCP connections open for this origin, which is the limit. Applies to HTTP/1.0 and HTTP/1.1 only. - The browser is briefly allocating space in the disk cache

  • Stalled: The request could be stalled for any of the reasons described in the Queueing.

  • DNS Lookup: The browser is resolving the request's IP address.

  • Initial Connection: The browser is establishing a connection, including TPC handshakes/retries and negotiating an SSL.

  • Proxy negotiation: The browser is negotiating the request with proxy server.

  • Request sent: The request is being sent

  • ServiceWorker Preparation: The browser is starting up t he service worker.

  • Request to ServiceWorker: The request is being sent to the service worker.

  • Waiting (TTFB): The browser is waiting for the first byte of a response. TTFB stands for Time for First Byte. This timing includes 1 round trip of latency and the time the server took to prepare the response.

  • Content Download: The browser is receiving the response, either directly from the network or from a service worker. This value is the total amount of time spent reading the response body. Larger than expected values could indicate a slow network, or that the browser is busy performing other work which delays the response from being read.

  • Receiving Push: The browser is receiving data for this response via HTTP/2 Server Push.

  • Reading Push: The browser is reading the local data previously received.