TLS Handshake Latency
TLS handshake latency is the delay caused by negotiating an encrypted HTTPS connection before any application data is sent. The client and server exchange messages to agree on ciphers and verify certificates, costing one or more network round trips on top of TCP setup.
Technical Architecture & Deep-Dive
On a mobile connection with a 150 millisecond round trip time, TCP plus a TLS 1.2 handshake can take over 400 milliseconds before the first request byte is sent. TLS 1.3 reduces this to one round trip, and session resumption can make it zero.
The biggest improvement comes from distance: terminating TLS at an edge location 10 milliseconds away makes each round trip nearly free, while the edge reuses already-established secure connections to origins.
Key Architectural Benefits
Implement TLS Handshake Latency at the Edge
Deploy lightweight API aggregation, edge caching, and secret injection in minutes without Docker containers or complex servers.
Frequently Asked Questions
Q:Does TLS slow down APIs significantly?
The encryption itself is cheap on modern hardware. The cost is mostly round trips during the handshake, which edge termination and connection reuse minimize.
Related Architecture Concepts
Time to First Byte (TTFB) measures the time between a client sending an HTTP request and receiving the first byte of the response. It includes DNS lookup, connection setup, TLS negotiation, network travel, and server processing time, making it a core indicator of backend and network responsiveness.
HTTP/3 is the latest version of HTTP, built on QUIC, a transport protocol running over UDP. QUIC combines connection setup and TLS encryption into fewer round trips and handles each stream independently, so packet loss on one request does not stall others.
HTTP keep-alive, or persistent connections, keeps a TCP connection open after a response so subsequent requests to the same host reuse it. This avoids repeating TCP and TLS handshakes for every request, significantly reducing latency for clients that call the same API repeatedly.