View the timing breakdown of a request To view the timing breakdown of a request:
Click the URL of the request, under the Name column of the Requests table. Click the Timing tab. See Preview a timing breakdown for a faster way to access this data.
The Timing tab. See Timing breakdown phases explained for more information about each of the phases that you may see in the Timing tab.
Preview a timing breakdown To view a preview of the timing breakdown of a request, hover over the request’s entry in the Waterfall column of the Requests table.
See View the timing breakdown of a request for a way to access this data that does not require hovering.
Previewing the timing breakdown of a request. #Timing breakdown phases explained Here’s more information about each of the phases you may see in the Timing tab:
Queueing. The browser queues requests when: There are 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 Queueing. DNS Lookup. The browser is resolving the request’s IP address. Initial connection. The browser is establishing a connection, including TCP handshakes/retries and negotiating an SSL. Proxy negotiation. The browser is negotiating the request with a proxy server. Request sent. The request is being sent. ServiceWorker Preparation. The browser is starting up the 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 To 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. #View initiators and dependencies To view the initiators and dependencies of a request, hold Shift and hover over the request in the Requests table. DevTools colors initiators green, and dependencies red.
Viewing the initiators and dependencies of a request. When the Requests table is ordered chronologically, the first green request above the request that you’re hovering over is the initiator of the dependency. If there’s another green request above that, that higher request is the initiator of the initiator. And so on.