Hva er TTFB (Time to First Byte)?
Rask definisjon
TTFB måler tiden fra en nettleser ber om en side til den mottar den første databyten fra serveren, og fungerer som en indikator på serverrespons.
Time to First Byte (TTFB) is a performance metric that measures the duration between a user's browser sending a request and receiving the very first byte of the server's response. It captures three phases: the time to send the request, the time the server takes to process it, and the time for the first byte to travel back.
A good TTFB is under 200 milliseconds. Between 200-500ms is acceptable, and anything over 600ms indicates a performance problem. Google considers TTFB when evaluating page experience, though it's not one of the Core Web Vitals.
Several factors affect TTFB. Server processing time depends on how long it takes to run database queries, execute server-side code, and generate the response. Network latency is the physical travel time between the user and server (which a CDN can reduce). DNS resolution time is how long it takes to convert your domain name to an IP address.
Common causes of slow TTFB include overloaded or underpowered servers, unoptimized database queries, lack of server-side caching, slow third-party API calls during page generation, and no CDN (meaning all requests go to a single origin server). Each of these can be diagnosed and improved with targeted optimizations.
Hvorfor det betyr noe
TTFB is the starting gun for your page load. Nothing else can happen until the browser receives that first byte. A slow TTFB delays everything: the HTML document, the CSS, the JavaScript, the images. It's the foundation that all other performance metrics build on.
For businesses, TTFB directly impacts user experience and conversion rates. If your server takes 2 seconds to respond before the browser can even start rendering the page, users on slower connections might wait 5+ seconds for a usable page.
Eksempler fra virkeligheten
A WordPress site with a TTFB of 1.8 seconds implemented server-side caching and reduced it to 150ms, cutting total page load time by more than half
An e-commerce platform discovered their TTFB was 900ms due to slow database queries; adding database indexes and query caching brought it down to 120ms
A media site moved their origin server from a single US location to a CDN with edge caching, reducing TTFB for European users from 800ms to 80ms
A SaaS dashboard reduced their TTFB from 1.2 seconds to 200ms by pre-computing frequently accessed data and caching the results
Relaterte termer
Core Web Vitals
Core Web Vitals er tre spesifikke måleverdier definert av Google som måler den faktiske brukeropplevelsen på nettsteder: innlastingsytelse (LCP), interaktivitet (INP) og visuell stabilitet (CLS).
CDN (Content Delivery Network)
Et CDN er et geografisk distribuert nettverk av servere som leverer nettinnhold til brukere fra den serveren som er nærmest dem, noe som reduserer lastetider.
Caching
Caching er prosessen med å lagre kopier av data eller filer på et midlertidig sted, slik at fremtidige forespørsler kan betjenes raskere.
LCP (Largest Contentful Paint)
LCP måler tiden det tar for det største synlige innholdselementet på en side, som et hero-bilde eller en overskrift, å bli fullstendig gjengitt.
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