Introduction to TTFB
Time to First Byte (TTFB) isn’t one of the Core Web Vitals, but it feeds into all of them. At Uxify, we use TTFB as a core checkpoint for diagnosing backend and network latency - especially when looking at poor LCP or slow regional performance.
TTFB measures the time between a user requesting a page and the first byte of response coming back from the server. It includes DNS lookup, TCP handshake, TLS negotiation, server processing, and network delays. It’s essentially the starting gun for page rendering - if TTFB is slow, everything else is stuck waiting.
Healthy TTFB
To deliver a responsive experience, the 75th percentile (P75) of Time to First Byte (TTFB) should be under 0.8 seconds. This ensures 75% of your users get a response from the server quickly. Here’s how Uxify categorizes TTFB performance:
LCP Range | Status |
0 – 300ms | Excellent |
300 – 800ms | Good |
800– 1500ms | Needs Improvement |
1500ms and above | Poor |
How TTFB matters
Two words: users and Google. Let’s start with your users. A fast TTFB means less waiting, quicker load, and smoother interaction. When TTFB is slow, users feel the delay before anything even appears - and that sets a bad tone from the start.
Then there's Google. While TTFB isn’t directly part of Core Web Vitals, Google does measure it and has flagged it as a contributing factor in page performance. More importantly, it’s tightly connected to LCP — a slow TTFB almost guarantees a slow LCP. So yes, fixing TTFB is critical to getting the rest of your vitals in shape.
Top 3 reasons for failing TTFB
Here are three of the most common and actionable reasons we see for high TTFB in Uxify Experience:
Low cache hit ratio
Sites without a proper caching strategy often have TTFB over 1s. You want your cache hit ratio to be 90% or higher.
Slow regions or edge locations
You might have fast TTFB in the US, but what about Brazil, India, or Australia? Slow TTFB in certain regions is often due to missing edge caching or underperforming hosting locations.
Server-side processing delays
Database queries, dynamic page generation, or inefficient backend logic can all stall your TTFB.
Uxify Experience gives you 80+ TTFB lenses across caching, location, traffic type, and more. Use it to zero in on backend bottlenecks. Then layer on Navigation AI or better CDN strategies to accelerate that first byte.