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Why Should I Do Web Performance Testing?

by Ryan Irelan

You hear a lot about web performance testing but you’re still unsure why you should spend the extra time (and money) doing this type of work. How does it add value to you project? How can you convince your client or boss that it’s a good use of time and money?

There are a lot why you want to do performance testing but these three are the most important reasons. They are also broadly applicable to most projects.

The three performance testing reasons are:

  • Search Engine Optimization (SEO), specifically ranking in Google and how it weights page speed in rankings.
  • User experience. We will approach performance as a feature in the website just like the design would be for the functional features of the website would be.
  • Economic use of bandwidth and server resources. This one will be less of a focus for us because we won’t be doing any heavy-duty server load testing however it will be important to make sure that our sites are as performance and lean running as possible. High traffic sites with poor performance can expensive to run and maintain.

Let’s talk about each of these three reasons for performance testing a little bit more.

SEO and Google

More than five years ago, Google announced that it was going to eventually include page speed as part of its ranking algorithm for organic Google search results.

The reason for this is clear: slow pages tend to be abandoned by visitors rather quickly. If you look at a page that may take, let’s say five seconds to load, most users will abandon that page and not even try to pursue it again.

If that page was listed at the top of the rankings for a certain search term on Google, then that search results page will no longer be as valuable to the user as it would be if all of the results at the top of the list were fast accurate and relevant.

Google prides itself on providing accurate relevant and good search results. That’s one of the reasons that it became the most popular search engine on the web! If Google served results that are accurate and relevant but slow to load, causing the users to wait a long time to see the page, then that threatens the very thing that made Google so popular in the first place.

In fact, Google even tested out user behavior with slower search results returning.

Back in 2009 they tried a test where they slowed down the search results page so it served a slower page to some visitors. What they found was that their experiment “demonstrated that slowing down the search results page by 100 to 400 ms has a measurable impact on the number of searches per user.”

As Google slowed down the page speed the engagement of their users decreased. When you search Google you are after an answer—the search result or relevant page—and you want to get there as fast as you can. It’s not a surprise that slowing down the results page caused a drop off in the number of searches.

Who wants to sit and wait for a page to load? Do you find that enjoyable? I certainly don’t.

Google reaffirmed their belief that performance matters. And in a big way.

As part of the performance initiative, Google added the PageSpeed Insight, which is a freely available tool for measuring your page speed and getting recommendations for how to improve performance.

In summary:

  • Google measured slow performing search results pages and noticed negative visitor behavior.
  • Google gave us a tool to measure and improve our page speed.
  • Google now cares how fast its pages are, and yours, too.

User Experience & Project Process

Performance is a design feature. -Brad Frost

Just like with Google and the noticeable change in user engagement when they increase the page time for the search results, having a slow performing website or webpage also decreases the user experience on your site.

If we think of web performance as another part of the project, just like we would think about the user experience, information architecture, and the design, we are less inclined to neglect performance during the project pushing it off to be something that we just handle later on after the site is complete and implemented.

By making Web performance something that matters as part of the user experience and design, we are then forced to consider it very early on in the project.

In the old days, and by that I mean 5 to 10 years ago, a typical project methodology was the waterfall process. Each discipline would do their work and then pass it down the line to the next discipline. Decisions were not made inter-disciplinary, instead in a silo of each discipline.

Designers were working in a silo without any consideration or understanding of what it would take to develop the features that they designed. Developers were working in their silo without communicating with designers on implementation details that might impact their designs. This includes how a design decision would impact the implementation when done within the bounds of the agreed timeline and budget.

A certain feature, as designed, could require twice as many database queries or some API that will add overhead, which in turn could slow down the performance of the page. It could also mean that the developer would need extra time to implement proper caching and other performance enhancements on the back-end in order to make the feature acceptably performant.

But now, a trend in the work of people to whom I’m connected—and I’d argue this is an industry-wide trend—is that designers and developers are working closer together so that they are making the decisions on the features of the website in unison. Developers can help influence and inform the designers decisions for both visual design and user experience design. And designers can work closely with developers on the implementation of their designs.

This new trend is encouraging. It is not only encouraging because we are all more focused on working together as a team but also because it helps us create better performing websites at beginning of the project instead of waiting until the end, as spackled-on, last-minute consideration.

When you wait until the end to consider performance you have the weight of all of the decisions of the entire project on your shoulders pressing down and preventing you from really making it absolutely best decisions for performance.

When we wait until the end for performance improvements we usually need to pull in more technology and resources, some of which can be very expensive, instead of designing and implementing a performant website from the beginning.

Performance is both a design feature and a way of working.

Bandwidth and server resources

Just add another server. Add more RAM. -Someone, somewhere

We design, code, and build the new website and start testing it. If it’s not fast we look immediately at more server resources as the solution.

We increase memory, increase bandwidth, we offload assets to a CDN, we move the database to a dedicated server.

All of these solutions are expensive. And maybe not even necessary.

These solutions are especially expensive if you’re working on a site that gets high traffic and requires infrastructure beyond just one virtual server or some cheap shared hosting.

Just because a high traffic website will need some additional services to run properly doesn’t mean we can slack on performance.

In fact, the converse is true. The higher traffic the site the more careful we have to be about performance.

Increasing server resources is, of course, unavoidable if the website traffic requires it. But for a site that serves tens of thousands, hundreds of thousands, or even millions, of visitors in a month, making sound user experience and design decisions with performance in mind can literally save thousands of dollars in costs.

( has a small part of its test results that shows how expensive your site is in consuming resources.)

If you’re doing client work, you can literally save your clients a lot of money by keeping web performance in mind throughout the project. And, since client work is always done in the service of the clients needs and requirements, saving the money is definitely a good thing.

Those are the three reasons to web performance testing:

  • Search Engine Optimization (SEO)
  • User experience.
  • Economic use of bandwidth and server resources.

The three core pieces of launching a successful and sustainable website.

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Filed Under: Web Performance Testing, Performance Testing