Send

Time spent writing the request onto the wire.

For most requests this is small, because the request itself is small. It grows when the request body is large -- a file upload, a big JSON payload -- or when the client's outbound bandwidth is the bottleneck, since every byte of the body has to be written before the server can start responding.

Other timing phases

• Blocked — Time spent queued before the browser could even open a connection for this request.
• DNS — Time spent resolving the hostname to an IP address.
• Connect — Time spent establishing the TCP connection, including the TLS handshake for HTTPS.
• SSL / TLS handshake — The portion of connect time spent negotiating TLS, shown separately for inspection.
• Wait (TTFB) — Time between the request finishing transmission and the first byte of the response arriving.
• Receive — Time spent reading the response body after the first byte arrived.