Master this key indicator of server performance and user experience
TTFB (Time To First Byte) is the time elapsed between when the browser sends an HTTP request and when it receives the first byte of the response. It's a fundamental indicator of your backend infrastructure performance, revealing the time needed to process a request and start sending data.
A high TTFB directly impacts user experience and SEO. Even if the rest of the page loads quickly, a slow server delays the entire rendering process. Google uses TTFB as a component of Largest Contentful Paint (LCP), one of the Core Web Vitals that influence ranking.
Understanding TTFB components allows you to target optimizations. MoniTao measures your endpoint TTFB continuously and alerts you when it exceeds your thresholds, allowing you to react before degradation affects your users.
TTFB is not a monolithic block. It breaks down into several phases, each of which can be optimized:
Google and web experts have established TTFB thresholds to evaluate performance:
Many factors can increase or reduce your TTFB:
Here are several methods to precisely measure your site's TTFB:
# With curl - detail of each phase
curl -w "\nDNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTLS: %{time_appconnect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n" -o /dev/null -s https://example.com
# Repeated measurement for average
for i in {1..10}; do
curl -w "%{time_starttransfer}\n" -o /dev/null -s https://example.com
done | awk '{sum+=$1} END {print "Average TTFB: " sum/NR "s"}'
# In Chrome DevTools
# Network → click on request → Timing
# "Waiting (TTFB)" = server time
# With PHP for internal debug
curl breaks down times into phases, allowing you to identify if the problem comes from DNS, network, or server. The X-Server-Time header on server side helps measure pure processing time.
MoniTao offers several features to monitor your TTFB:
Yes, indirectly. Google doesn't measure TTFB directly but uses LCP (Largest Contentful Paint) in its Core Web Vitals. High TTFB delays LCP, which can penalize your ranking. Google recommends LCP < 2.5 seconds.
This is normal. TTFB depends on many variable factors: server load, cache state, network congestion, database queries. Analyze trends and averages rather than isolated values.
For cached static content, yes. For non-cacheable dynamic content, the CDN can even add slight latency (extra hop). Analyze whether your content can be cached at CDN level.
MoniTao measures time between sending the HTTP request and receiving the first response byte. This includes DNS resolution, TCP connection, TLS negotiation, and server processing time.
TTFB measures time to first byte received. Total response time includes the complete body download. For a 50KB HTML page, response time will be TTFB + time to download the 50KB.
TTFB only measures server time. Slowness may come from frontend: heavy JavaScript, unoptimized images, render-blocking CSS. Analyze the full waterfall with DevTools or WebPageTest.
TTFB is an essential indicator of your backend health. Low TTFB means your server responds quickly, allowing the rest of the loading chain to start early. The goal should be TTFB under 200ms for most pages.
TTFB optimization involves several levers: CDN for network latency, application cache to avoid repeated calculations, database optimization for queries. MoniTao allows you to monitor your TTFB continuously and be alerted as soon as it exceeds your goals.
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