Time to First Byte (TTFB) is a metric that reflects how quickly a browser can connect and download data from your servers. By tracking TTFB timings across your site, you can detect any slowdowns or issues with your servers that negatively affect your performance.

TTFB may not be a Core Web Vital, but it's still a crucial site performance metric that everyone should track. Poor TTFB indicates that your servers aren't responding quickly enough, which can cause cascading performance issues for the entire page-loading process. That time isn't just annoying—it could directly lead to visitors bouncing and checking out a competitor.

This guide will give you everything you need to know about the Time to First Byte metric: how it's measured, why it's important, and how to improve it. With this knowledge, you'll be ready to create a snappy site experience for your visitors.

What does TTFB measure?

TTFB measures the amount of time between when a visitor clicks a link or hits enter on their keyboard and when that page's first byte is downloaded.

For most people, this process will (hopefully) feel instantaneous, but several things are happening behind the scenes. A page's TTFB is the sum of all of the following tasks:

• Redirect time: The time it takes to resolve any URL redirects in place, i.e., when a URL has been moved by a 301, 302, etc.
• Service worker startup time: Not applicable in all cases. Service worker APIs are similar to a proxy server in that they execute in browsers and can modify requests before or after they're returned from the server.
• DNS lookup: The DNS lookup translates the words we use for URLs, like calibreapp.com, into an IP address that your browser can use to download the correct webpage.
• Connection and TLS negotiation: The time it takes for the browser and server to form a connection so data can be sent over.
• The request: The process of the browser requesting data from the server and the server sending it back. TTFB stops measuring after the first byte makes it over.

It's important to note that TTFB can differ greatly based on many factors when people access your site. The further a person is from the server, the longer it takes for data to physically make it to them. For this reason, a person in Sydney and London can get radically different TTFB times and have very different experiences on your pages.

Why should you improve your TTFB?

TTFB is the backbone of page speed. Good TTFBs may not ensure a quick load time, but bad ones are enough to make a site feel slow—and people don't like slow sites. According to a study by Google, even a single added second can increase bounce rates dramatically. To give your pages a chance at impressing readers, your TTFB needs to be as quick as possible.

A slow site doesn't just increase bounces—it also influences your site rankings on Google. Google has stated that its search engine considers page experience a ranking factor. Sites are judged for good experience based on several factors, one of which is the Core Web Vitals—a set of performance metrics that partially rely on TTFB.

For instance, Largest Contentful Paint (LCP) is a Core Web Vital that measures how long it takes to load the most data-intensive element on the above-the-fold portion of your page. If your page takes a long time to download data from your server (i.e., your TTFB is slow), your LCP score will be worse. Google will take that as a negative page experience signal, affecting your search rankings.

What is a good TTFB?

Faster is always better when it comes to TTFB. Most pages should aim for TTFBs that are less than 800 ms. Any longer than 800 ms, you'll risk having noticeably slow load times.

Remember that every page on your site will have different TTFBs and that these scores depend heavily on visitor location. For this reason, it's important to regularly test your site's pages using different locations to catch any pages that fall below the 800 ms benchmark (more on that later).

5 ways to improve TTFB

To lower your TTFB, you'll need to shave valuable milliseconds off one or more of the processes before your first byte loads. Here are a couple of ways you can do that.

1. Upgrade your hosting or servers

This step is the most important thing you can do to make a noticeable improvement in your TTFB. By investing in better hosting or servers, you'll be able to speed up connection times and get data over to browsers more quickly.

In some cases, all you'll need to do is upgrade your servers. If your performance is constrained by memory or CPU limitations, an upgrade could be precisely what you need for better TTFB outcomes.

In other cases, changing your hosting provider might be a more appropriate fix. However, it's not always clear what makes one hosting provider better. When evaluating different hosting options, you should consider whether they:

• Offer dedicated servers.
• Have CPU, memory, and GPU specs superior to the competition.
• Own servers located close to where your site visitors are located.

2. Use a Content Delivery Network (CDN)

CDNs improve TTFB because they allow you to keep your content cached on their globally distributed network of servers. With access to more servers, you should be able to serve visitors more quickly (a visitor's physical proximity to a server impacts how long it takes for data to get to their browser).

CDNs also help you by automatically:

• Reducing the number of requests your origin server has to deal with, resulting in less load.
• Shrinking file sizes to make for quicker transfers.
• Optimising server settings for faster speeds.

3. Reduce DNS lookup time

DNS lookups are an essential part of the page-loading process as they translate the URLs people use into the IP addresses used by computers. Before servers can send back the first byte of data to a browser, they need to do this check. For this reason, optimising the DNS lookup process helps you shave time off your TTFB.

Some ways to reduce your DNS lookup time include:

• Ensuring your DNS records have long-term TTL records, which allows DNS to be cached for at least 24 hours.
• Using dns-prefetch to reduce potential delays during page load.
• Removing any page redirects.
• Caching commonly used elements like font or CSS files.

4. Always default to server-side rendered HTML

Adjusting server or cache settings is far more complicated than other options on this list. However, for best TTFB results, your servers need to be optimised to get your data out the door as quickly as possible.

One way to make your servers react more quickly is to use Server Side Rendering (SSR). SSR means that pages are rendered on the server and then sent whole over to the browser. With frequently updated pages, you can leverage SSR to render pages in advance, cache them for a set amount of time, and then quickly send over the page when the browser requests it.

5. Use prefetching or preloading

Prefetching or preloading is a technique that involves loading resources, such as images, scripts, or stylesheets, before they are actually needed by the user. By doing so, the resources can be stored in the user's browser cache, allowing for faster retrieval when they are actually requested.

Prefetching or preloading can significantly improve TTFB by reducing the amount of time it takes for the browser to fetch and load resources. This is because the resources are already available in the cache, eliminating the need for the browser to make additional requests to the server.

By implementing prefetching or preloading, website owners can proactively optimize TTFB by reducing the number of requests and improving the overall loading speed of their web pages. This can result in a faster and more responsive user experience, ultimately enhancing user satisfaction and engagement.

Conclusion

In conclusion, improving Time to First Byte (TTFB) is crucial for enhancing website performance and providing a positive user experience. TTFB measures the time it takes for a browser to connect and download data from servers, and a slow TTFB can lead to slower page load times and increased bounce rates. Additionally, TTFB is a factor considered by search engines like Google when determining page rankings, further emphasizing its importance.

To improve TTFB, there are several strategies that can be implemented. Upgrading hosting or servers can significantly reduce connection times and improve data transfer speeds. Utilizing a Content Delivery Network (CDN) allows for content to be cached on globally distributed servers, reducing the distance data needs to travel and improving response times. Optimizing DNS lookup time, such as using DNS prefetching and reducing page redirects, can also contribute to faster TTFB. Additionally, utilizing server-side rendering (SSR) and implementing prefetching or preloading techniques can further optimize TTFB by loading resources in advance and reducing the need for additional server requests.

By implementing these strategies, website owners can effectively reduce TTFB and provide a snappy site experience for their visitors. Monitoring and regularly testing TTFB across different locations can help identify any pages that fall below the recommended benchmark of less than 800 ms. By prioritizing TTFB optimization, website owners can improve performance, increase user satisfaction, and potentially boost search engine rankings.