TCP Connection Time

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Created: August 17th 2015

connectStart connectEnd requestStart TCP Connection Time

What is TCP connection time?

  • TCP connection time measures the time taken to establish the transport connection as well as other time intervals such as SSL handshakes.
  • More simply put, it is the time it takes a browser to establish a connection with a server.
connectstart, secureConnectionStart, and connectend

Connection time = Establishing a connection

TCP connection time measures only the establishment of a connection, not the use of that connection.

connectstart, connectend, and requeststart

In the above image TCP connection time is measured on the left (connectStart to connectEnd).

Three events

The TCP connection time includes...

How is TCP connection time calculated?

The entire TCP connection time can be measured using the connectStart event and the connectEnd event.

It is notable that TCP connection time includes the SSL handshake (the establishing of a secure connection).

The SSL time can be measured using the secureConnectionStart event and the connectEnd event.

How to optimize TCP connection time

The best optimization would be to get rid of as many connections as possible, thereby completely removing this process from a timeline.

The pagespeed optimizations that may used to do so are:

Establishing connections (especially SSL handshakes) can benefit from a robust responsive server.

Patrick Sexton by