Top Ten Website Performance Metrics

Ben Faw , Co Founder at BestReviews & Contributing Writer Reading estimate: 8 minutes

The Top Ten Website Performance Metrics

If you’re like most business owners, you’ve probably spent a lot of time and money developing your website. There’s a good reason for this. Your website is an incredibly valuable resource — being the biggest way to reach your customers on a daily basis and perhaps, the greatest marketing tool at your disposal. It only makes sense to ensure your website is always performing at its best, no matter what is going on. 

However, your website’s performance can fluctuate depending on any number of factors. This is why it is important to pay attention to your website’s performance metrics. Your website’s performance metrics will give you incredible insight into how it is doing and if there are improvements that need to be made, so it will run better for future visitors to your site.  However, you may not even realize just how important these metrics are and what small fluctuations in performance can mean. This is why we break down these vital performance metrics below, including what you should know about them and what they indicate about the performance of your website.

1. Page Speed

Page speed is one of the most important metrics to be aware of, and it can have a far greater impact than you may even realize.  Simply put: People don’t like waiting around! Keep your page speed as fast as possible to retain as large of an audience as possible. 

Have you ever gone to a new website, only to have it stall during the loading process? This is a frustrating process and one we’re all extremely familiar with. Slow page speeds are a part of life for all Internet users, but if your site is suffering from slow page speeds, you need to find ways you can start speeding things up — immediately. Slow page speeds are one of the quickest ways to get people to turn around and leave your site, no matter what it is you have to say or what you have to sell them.

From a technical perspective, Page speed is the time it takes for a page to load and has three different metrics it consists of:

  • Server response time often called time to first byte (TTFB)
  • Time it takes to download an HTML web page — also referred to as transfer time
  • Duration of time it takes to render the web page in a browser

Ultimately, page speed refers to the entire time span, from sending an HTTP request to a server to the complete and final display of the web page on a browser. 

2. Time to Title

Similar to your page speed, the time to title is the amount of time it takes for a website’s title to appear in a browser tab after an individual requests a website. In addition to testing an individual’s patience, the longer it takes for a page’s title to appear makes a website appear less legitimate.

While this may seem like a rather small and insignificant detail, time to title can help assuage any concerns or anxiety about a site being reputable, so it's an important metric to pay attention to. 

3. Time to Start Render

The time it takes from an individual making a request and the amount of time it takes for content to begin loading — even if it does not fully load — is called the time to start render. It's very similar to the last metric that makes up page speed — the time it takes for a site to render — but, it's not the full duration it takes to render, only the time it takes to start loading. 

This metric is also quite important, because even if the content on a page does not fully load, an individual is more likely to stay on a page if they see content begin to appear. While a site visitor's patience may still be tested if it takes too long for everything to load, a quick time to start render can be enough to keep people interested and keep them around on your site. 

4. Time to Interact

Another metric that has everything to do with users’ patience is the time to interact. It refers to how much time it takes before individuals can begin to click on links, type in text fields, scroll on a page, and interact in other ways with a website. As you can imagine, this is another important metric because the quicker an individual can begin to interact with a web page, the less likely they are to leave the page, even if the page has not rendered fully. 

A real-world example would be if you added an item to your cart while shopping online, then immediately went to the checkout. The time it takes for the checkout button or link to appear and be functional would be the time to interact in this situation. 

5. DNS Lookup Speed

You’ve likely heard of “DNS lookup speed” or “DNS lookup time,” but you may not fully understand what this metric is. This refers to the amount of time it takes for your Domain Name System (DNS) provider to translate a domain name into an IP address. It’s important to note that there are faster and slower DNS providers out there, and if you’re using a slower provider, it can vastly slow down your DNS lookup speed.

There are plenty of free online tools at your disposal to test your DNS lookup speed, and going with a premium DNS provider ensures you have a faster DNS lookup speed.  We recommend you find the fastest DNS provider possible. 

6. Bounce Rate

Your bounce rate is pretty much what it sounds like. People are “bouncing” away from your site without thoroughly searching through it, and sometimes without even taking the time for the site to load properly. It can also be defined as a single page visit to your site, with users failing to interact elsewhere. This often (though not always) means there is an issue with your site’s load times or a similar issue that needs to be urgently addressed.

If you identify a high bounce rate, it’s well worth taking a look at your other metrics pronto — especially those with a tendency to affect the amount of time your visitors stay on your site. Typically just a few simple site improvements will be enough to retain visitors for a longer period of time, subsequently improving your bounce rate. 

7. Requests Per Second

Also sometimes referred to as “Throughput” or “Average Load,” this metric refers to the number of requests your server receives every second. It is a rather basic metric used to measure the main purpose of your server, and those working on a large scale can reach upwards of 2000 requests per second. It will let you know the pressure your web application is operating under and if any adjustments need to be made.

8. Error Rate

It is inevitable some errors will occur on your site at any given time. Your error rate measures the number of errors occurring at any given time, keeping track of how many occur within a specific time frame. This can give you an idea of not only how many happen on average, but it can also let you know when errors tend to increase. For example, errors may occur more frequently when you have more users on your site, such as during special promotions. Knowing when they occur and what to look out for can help you prevent possible problems and minimize even bigger problems that could potentially arise.

9. Time to First Byte/Last Byte

We briefly touched on time to first byte as a subset of page speed, but it's an important enough metric to warrant its own breakdown. 

Among the more important pieces of information to take note of is how long it takes for the first bit of personalized information to reach a user’s web browser, which in this case is referred to as the time to first byte or TTFB. Google recommends your TTFB remain under 200 milliseconds (ms) or less. 

While all static information on a site will generally reach all users quickly, personalized information can take a little longer, making this an important metric to consider. Slight alterations in your code can boost how quickly this information can arrive. Likewise, time to last byte or TTLB refers to the moment when a user has received all of their information, and similarly, the quality of your code plays a vital role in how quickly this occurs. 

10. Conversion Rate

Last but not least, we can’t discuss metrics without talking about conversion rates. This refers to how many unique visitors end up converting into customers. Various factors affect conversion rates, but it is impossible to determine everything that plays a role in what transforms a site visitor into a customer.

The conversion rate simply refers to the number of unique site visitors divided by conversions. However, among the many factors that can play a role in conversions are the overall user experience (UX) on your website, getting the right kind of traffic and visitors to your website, having good speeds on your website, using a great call to action, and so many more important variables. There are many ways you can continually improve your conversion rates and get more of your site visitors to transform into customers, which is the primary goal when building your website. 

In Conclusion

It is vital to continually measure your website’s metrics to know how successful your website is performing at any given time. While you can continue to work on your website day in and day out, you will never know how well it is doing unless you keep an eye on these metrics and monitor them regularly. As you make improvements, note the performance of all your metrics in response to these adjustments. This will be a better gauge than anything else of whether your improvements are truly what is needed to help maximize your conversions and boost sales. 

Though it may seem like a tremendous undertaking, it is something any web development team can do given enough time and talent. These ten website performance metrics, while not the only ones worthy of consideration when building and developing your site, are vital to bear in mind — to ensure your website is able to succeed in today’s hyper-competitive online marketplace.

For more information, check out Pantheon's Speed Test — it's a great starting place for evaluating your site's performance and making your visitors happy. And if you're looking for fastest hosting platform on the planet for Drupal and WordPress sites, look no further than Pantheon's high-performance hosting

Discover More

Opt In Now For a Faster Build Pipeline on Front-End Sites

Steve Persch
Reading estimate: 2 minutes

Pantheon Increases PHP Memory Limits for Performance and Elite Plans

Rachel Whitton, Developer Experience
Reading estimate: 2 minutes

Pantheon Includes Object Cache Pro for Painless Improved Performance

Steve Persch
Reading estimate: 3 minutes

Try Pantheon for Free

Join thousands of developers, marketers, and agencies creating magical digital experiences with Pantheon.