July 11, 2018

Time To First Byte (TTFB) is the time it takes for a web server to respond to a request. It’s a metric reported by several page speed testers. It is also often quoted as being a primary means for measuring how fast a site is. The idea being that the faster a web server responds, the quicker a site will load.

However, numerous groups have found that TTFB isn’t that important. When looked at in isolation, the figure provides an appealing way to grade your site or hosting provider. However, when looked at in conjunction with other metrics, there seems to be a disconnect. This is especially true with regards to SEO rankings and improved user experience.
Here, we’re going to look at why TTFB can be easily manipulated, what metrics actually matter, and how knowing these things can help you to improve your site’s SEO, user experience, and more.

What Does Time To First Byte Measure?

TTFB measures the time between a user making a HTTP request and the first byte of the page being received by the user’s browser.

What Does TTFB measure

The basic model of how TTFB works

The model is simple. The faster a web server responds to a user request, the faster the site will load. Unfortunately, things get a little more complicated.

Time To First Byte Test

In some cases of testing site speed, you’ll find TTFB test durations far longer than what you would expect. This is despite actual page load times seeming much faster. This is the first indication that something is wrong with how TTFB measures speed.

A deeper look shows TTFB actually measures the time it takes for the first HTTP response to be received. It does not measure the time it takes for the whole page to be sent.

Time To First Byte test

A test of Time To First Byte and page load times

In the Time To First Byte test above, TTFB is measured at 0.417 seconds, which seems very quick. However, looking at the waterfall, we can see that this figure only correlates with the HTML loading time.  Afterward, page load speed takes much longer for other assets on the page and we’re seeing DOM content loaded at around 1.6 seconds.

This is because the TTFB value is incredibly easy to manipulate. HTML HTTP response headers can be generated and sent incredibly quickly but they have absolutely no bearing on how fast a user will be able to see or interact with a page. For all practical purposes, they are invisible.

By loading HTTP response headers to speed up TTFB, it’s easy to create a ‘false’ view of a site’s speed. It also doesn’t necessarily mean that the rest of the waterfall will load quickly as well.

Speed Tests With NGINX

A good example of how Time To First Byte testing can be manipulated with HTTP headers is when looking at the page load times of NGINX in conjunction with compression.

Compressed pages are smaller and so they download from a server faster when compared with uncompressed pages. This ultimately means that page loads times to interactivity are much faster. However, from the perspective of TTFB, this is not true.


Time To First Byte compared with actual page loading times

This is because HTTP headers can be generated and sent relatively quickly before the main page content.

This is an especially significant figure for those that make use of the Nexcess Cloud Accelerator, as this makes use of NGINX in order to speed up caching speeds on optimized Nexcess platforms.

Continue reading to find out what metrics you should be using to check page load times.

What About Page Load Speed Does Matter?

In a 2013 study by Moz, it was found that Time To First Byte does have a significant correlation with SEO rankings. The faster TTFB was, the higher ranked pages would be.

This being said (and as Moz themselves make clear) correlation and causation are not the same thing. The actual methods Google (and other search engines) use to crawl web pages and build out SERPs are not known to the public.

It’s been deemed by many that page load times to interactivity are actually a lot more important. When looking at page speed tests, it’s important to look at all the figures available as a whole and not just TTFB.

So, with regards to TTFB tests, SEO, and user experience:

Google Does Not Measure Page Speed for SEO (Entirely)

Ok, it sounds like we’ve gone back on what we just said, but bear with us.

Google doesn’t measure page speed as incredibly important, it measures user behavior. They have said in the past that if users are willing to wait for content to load, they will not downgrade a website for being slow.

This is because Google weighs usability and experience as more important than speed. Back in 2010, Matt Cutts said that including site speed as a ranking factor “affects outliers […] If you’re the best resource, you’ll probably still come up.” It just happens to be that the less time a user has to wait for a page, the more likely they are to stay on the page.

So when it comes to using speed testing services such as PageSpeed Insights, make sure to consider your page load times from a practical perspective as well. How do you feel about the time it takes for your page to load when you type it in your browser? Do you think the content quality is worth the wait?

Time To First Byte SEO

PageSpeed Insights provides actionable speed intel for SEO such as that above

Simple checks like this are easy and can provide you with a lot of insight into what your users will think.


Practical Page Load Times Matter – Not TTFB

A faster Time To First Byte does not mean a faster website.

TTFB is not a practical measurement. It doesn’t really affect the user experience. The time it takes for a browser to communicate back and forth with a server doesn’t affect a user’s experience of that server’s content as much as the time it takes for them to actually interact with it.

Instead, measurements that test time to interactivity are inherently more important. Improvements here don’t always match the results of web page speed tests or scores.

So, the main takeaway here? High-quality content and a great user experience are still two of the most significant factors involved in SEO, site speed can influence this but is not nearly the most important. 


Mobile Speed is Now a Ranking Factor

As of July 2018, mobile page load speed has become a factor in SEO ranking. TTFB can be included in this.

However, again, TTFB and page load times aren’t as important as high-quality content and usability. The user experience on mobile devices has long been a key area Google and other search engines have tried targeting and improving. Load times are just a small part of this.

Responsive design and easily readable and scalable text and images are much more important.

Google highly recommend their tool PageSpeed Insights in order to properly see how your page speed may affect SEO ranking.


Slow and Steady Wins the Race

Ok, all this doesn’t mean that you should let your site crawl to a halt. This isn’t a childhood fable or a call to reduce quick internet. Fast internet is one of the wonders of the modern age and you still want your site to load as quickly as possible.

What we’re saying is that if you’re trying to find how to improve Time To First Byte, stop.

It’s far more important for you to start looking at page load time in their entirety and not just the time it takes for a server to respond. At Nexcess, we’re proud of how fast our data center serves content, and work our hardest to make sure that our servers are optimized for providing a great user experience and helping to boost your SEO as much as a hosting company can. 

We highly recommend checking out the Nexcess Cloud and seeing how Nexcess can help.

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Nexcess, the premium hosting provider for WordPress, WooCommerce, and Magento, is optimized for your hosting needs. Nexcess provides a managed hosting infrastructure, curated tools, and a team of experts that make it easy to build, manage, and grow your business online. Serving SMBs and the designers, developers, and agencies who create for them, Nexcess has provided fully managed, high-performance cloud solutions for more than 22 years.

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