What Does This Speed Test Measure?
This tool measures the server-side response time of any URL by making a real HTTP request from our server and recording precise timing for each phase of the connection. Unlike client-side tools that measure rendering and paint times, this focuses on network and server performance.
The timing waterfall breaks the total response time into five phases, each representing a distinct step in the HTTP request lifecycle.
Understanding the Timing Phases
- DNS Lookup: The time to resolve the domain name to an IP address. Uses your configured DNS resolver. Typically 10-100ms for cached lookups, 50-200ms for uncached.
- TCP Connection: The time to establish a TCP connection (the three-way handshake: SYN, SYN-ACK, ACK). Determined primarily by the physical distance between the client and server.
- TLS Handshake: The time to negotiate HTTPS encryption (certificate exchange, key agreement). TLS 1.3 requires one round trip; TLS 1.2 requires two. Only applies to HTTPS URLs.
- Time to First Byte (TTFB): The total time from request start until the first byte of the response arrives. Includes all previous phases plus server processing time. This is the most commonly cited server performance metric.
- Content Transfer: The time to download the complete response body after the first byte. Determined by response size and bandwidth.
How to Improve Website Speed
- Use a CDN to reduce DNS, TCP, and TLS latency by serving from edge locations near users.
- Enable HTTP/2 for multiplexed requests and header compression.
- Optimize server-side code — cache database queries, use connection pooling, and reduce computation.
- Enable TLS 1.3 for faster handshakes (1 round trip vs 2 for TLS 1.2).
- Use a fast DNS provider like Cloudflare (1.1.1.1) or Google (8.8.8.8).
- Compress responses with gzip or Brotli to reduce transfer time.
- Set proper caching headers so repeat visitors skip the full request cycle.
Who Uses Website Speed Tests?
Web developers use speed tests to identify server-side bottlenecks and verify that performance optimizations (CDN setup, caching, server upgrades) are working. DevOps engineers monitor response times to detect degradation before it impacts users.
SEO specialists track page speed because Google uses Core Web Vitals (including TTFB) as a ranking factor. Product managers monitor speed as a key user experience metric — research shows that a 1-second delay in page load reduces conversions by 7%.