How to test website speed and find elements that slow it down

Internet users aren’t patient. Only in exceptional situations will the slow functioning of a website not cause its users to immediately leave for the competition. Website’s speed is especially important for online stores or news websites. Their users will instantly find what they are looking for elsewhere.

People browsing the Internet on mobile devices are even less patient than those using their computers. For most of them waiting for the page to load for more than 10 seconds is too long.

Half of the online shoppers find the speed of the website to be — in addition to the offer and functionality of the site — a primary factor in building satisfaction. Almost every other e-store user is looking for another website when the waiting time exceeds 3 seconds.
Half of those dissatisfied with the website’s functioning tell other people about it. Every second of waiting means an increase in dissatisfaction. The website must work fast. Making sure that it does is worth it. Few users return to a website where they had negative experiences.

In addition, Google, aware of the expectations of Internet users, takes into account the time it takes for the page to load when evaluating it. That’s why it’s so important to check how fast the website loads and identify and eliminate the elements that may be slowing it down.

What factors influence website’s loading speed

The speed at which a website loads and gets displayed depends on factors such as:

  • specification of the user’s PC,
  • bandwidth of the user’s connection,
  • temporary load on the server and its connection,
  • server’s parameters and settings,
  • website design.

We can’t control all the factors — for example user’s PC and connection specifications or temporary server and connection load. Those that we can control are worth paying attention to at the stage of choosing the hosting service. Here, the key issue is the connection that the server uses to connect to the Internet.

Without changing the hosting service it’s possible to control the parameters and settings of the server and the design of the website itself. All these elements affect the speed of the website. In order to make any changes, we must constantly check how quickly the website is running and identify the elements the optimization of which will accelerate its operation.

Ad hoc measuring of website’s loading speed

Measurements done with a stopwatch aren’t reliable. Performing a reliable speed test requires the use of appropriate tools. Here are two particularly worth recommending.

Google Page Speed Insights is a simple tool which allows us to assess the speed of the website from the perspective of desktop and mobile users.

The results are expressed on a scale from 0 to 100. Apart from the measurement result, the application presents suggestions on what can be improved on the website in terms of server parameters and settings as well as the design of the website. Recommendations are divided into those that need to be improved (critical) and those that are worth improving (non-critical).

The biggest advantage of this tool is that you will see the page the way Google sees it — and websites are most often optimized for that search engine. It can be assumed that if the site is fast from Google’s point of view, it will also meet the expectations of the users.

WebPageTest is an advanced tool that accurately measures the speed at which a page loads in a real browser from a location selected by the user.

Here, the scale that describes the loading speed is different, it refers to school grades from D to A. The speed is evaluated in four dimensions.

WebPageTest shows, among others, load time during the first load vs load time during repeat visit (inclusion of cache effect) and time and order of loading individual page components.

The tool also shows which resources block the load of the rest of the page (waterfall graph), displays a breakdown into resource types (file types) and hosts/domains (and a number of calls), suggestions for fixing issues like Google, and screenshots.

The most common elements that slow websites down

The reasons for the slow operation of the page may be attributed to infrastructure (server, connection) or result from the website’s design. There are several elements that appear among Google Page Speed Insights and WebPageTest’s suggestions more often than others. It’s worth keeping them in mind at the stage of building the website and when developing future updates.

Unoptimized images

It is very important to optimize the images that are embedded on the page when it comes to the page loading speed. The key thing is to avoid publishing images that are too large (in terms of resolution).

It is helpful to use apps that reduce size using lossless compression — e.g. TinyPNG.

If new graphics are being published frequently (e.g. ads, news), you may want to check the site for images that may be slowing it down several times a day.

Non-minified code

The speed of loading a page is also affected by the size and weight of text files containing CSS, JavaScript, and even HTML code.

Their size can be significantly reduced. Minification mainly involves the removal of unnecessary characters — such as spaces or line breaks. Such code is less readable but works just as well as a version full of characters that are unnecessary from the programming point of view.

Code minification features are often built into larger applications but they are also available as separate tools such as Minify Code.

No cache usage

The speed of the page also depends on the level of optimization of its static content, i.e. the elements that are unchanged by the mechanisms of the page. They are mainly images, text files containing CSS or JavaScript code, and various downloadable files. Due to the fact that these files do not change, they can be stored in cache — both on the server side and in the browser.

In addition to enabling caching, for static files you can use a Content Delivery Network (CDN), a geographically vast network of servers caching our content. Thanks to them, users download static content from their nearest network node, which speeds up the loading of the page.
You could start with the free version of CloudFlare.

Constant speed monitoring

Optimization that allows for achieving good page speed results is a success. That does not, however, mean that it’s over. The site may, at some point, slow down. This can be caused, for example, by:

  • publishing a large, unoptimized image,
  • a significant increase in server load,
  • the occurrence of an error in the website’s construction,
  • server configuration error.

This is why you should constantly monitor your page loading times. This is one of the features offered by the best website monitoring services, e.g. Super Monitoring.
This service, when configured properly, in addition to the typical emergency situations (website unavailable, a malfunctioning feature, etc.) will detect page load delays and alert you by providing data for analysis that is similar to the one provided by WebPageTest described above.

The speed of the website is important for users and for Google robots. It needs to be measured, optimized and monitored, which in turn results in avoiding financial losses.

And who's monitoring your website?

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