Glossary · Performance

Connection Time

Connection time is the delay to establish a TCP connection, plus TLS for HTTPS, before the first byte of an HTTP request can be sent.

Updated October 6, 2026

Connection time is the time a client spends setting up a transport connection to the server before sending its request. For HTTPS over TCP it covers the TCP three-way handshake and the TLS handshake. Tools often report them as separate "connect" and "SSL" phases.

Why it matters

Both handshakes cost network round trips, so connection time scales with latency, not bandwidth. A TCP handshake takes one round trip. TLS 1.3 adds one more, and TLS 1.2 adds two. With a 100 ms round trip, a fresh HTTPS connection can spend 200 to 300 ms before any request is sent.

Reducing it means doing it less often or over shorter distances: reusing connections with keep-alive, using HTTP/2 multiplexing, serving from a nearby CDN edge, and using HTTP/3 (QUIC), which combines transport and encryption setup.

Example

Round-trip time: 80 ms
TCP handshake:   1 RTT = 80 ms
TLS 1.3:         1 RTT = 80 ms
Request starts at 160 ms; TTFB follows after server think time.

Common mistakes

  • Blaming server speed when the delay is in connecting.
  • Disabling keep-alive, so every request reconnects.
  • Serving from one distant region to a global audience.
  • Still allowing only TLS 1.2 or older.

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Keep reading

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