Monitor the four most common performance errors

Performance is often one of the biggest challenges in web development. Implementing all the features an agency's client wants is one thing, but building them to be fast is another. In this article we want to talk through the most common mistakes that are made.

It is also important to understand that you must not draw conclusions about others from yourself. Yes, the website will be fast during development. But this is also due to the fact that the web server might be installed locally on your own computer or at least very close to one. The internet line that is active in an agency should also not be average. At the latest when you have finished a project, you should try out the website under the following circumstances:

• In the country
• On the train
• On the smartphone

Too large images

The classics are pictures that are too large. Luckily also a challenge, which is the easiest to fix. There are many reasons why pictures can be too big. Often they are simply not optimized for the right height and width, but in their original size. Sometimes also in the wrong file format or meta files are still attached.

In order to find images that are too large, koality.io checks the pages every hour. This includes images that are loaded in the browser by JavaScript.

Too many assets

Sometimes it is not individual images that make a web page slow, but the sum of the loaded content. Many medium-sized illustrations can also cause the same problems, because even today there are enough situations where you have a bad internet connection.

koality.io adds up the sizes of all loaded content. This includes images, JavaScript files, CSS files, videos and everything else that can be found on the websites. As soon as the total size exceeds a set threshold, an alarm is triggered.

In addition, all measured values over the last month are displayed graphically so that changes in page size can be seen more easily.

Too many integrations

Not only the large content can slow down a website, but also the complexity. Meanwhile JavaScript integrations can be found everywhere. More and more is being built into the pages. Starting with Google Analytics or the Facebook pixel. All these tools need time in the browser and it is not always possible to parallel this.

Let's take a look at some of the most frequently used websites in Germany:

• otto.de - 19 integrations
• T-online.de - 37 integrations
• Bild.de - 34 integrations
• Tagesschau.de - 2 integrations
• Chip.de - 27 integrations
• Dhl.de - 1 integrations
• Wetter.com - 62 integrations
• Idealo.de - 20 integrations
• Immobilienscout24.de - 19 integrations

To evaluate whether a website is slow, you need objective measures. The classic one is the time-to-load in the browser, i.e. the time a browser takes to load all relevant content. However, in the meantime, it is no longer the technical speed of the website that is the relevant measurement, but the perceived speed. If a user finds that the page is fast, then it is fast. It is harder to measure, but it makes a lot of sense. After all, what does a user care that an advertising element still needs to be loaded but is not in the current viewport?

koality.io offers both values: the perceived and the technical speed. Both are measured continuously. For the technical speed the page is executed in a chrome browser, for the perceived speed we use the Google tool Lighthouse.

Slow servers

There are two reasons why websites are perceived as slow. First, what happens in the browser can take a long time, but there is another component: the server. This is where the actual website is assembled and then delivered. Most of what happens on the server. For this reason you have to be fast here.

Here you can scale very much by the number of CPUs and memory in the server. Sometimes hardware is cheaper than optimizing software.

It is important here that the values are continuously monitored. If the server time gets slow or changes a lot, you should immediately talk to the hoster or switch to a new, faster server. koality.io monitors exactly this and alerts you as soon as something unforeseen happens.

In the future, we will already offer solutions for the most common performance problems in koality.io. Then you can follow the appropriate instructions every time we find an anomaly.