Why Is Amazon Website So Slow? Here Are The Reasons

Amazon is the world’s largest online retailer, and one of the most valuable companies in the world with a market cap of more than a trillion dollars.

A speed report from Lighthouse paints a rather grim picture and scores the Amazon website 8.3 seconds on the speed index (SI), and 76 on Performance.

There are many reasons why the Amazon website is so slow. This includes:

  • Bloated JavaScript files
  • Absence of lazyloading
  • Unnecessarily large image files
  • Old Image formats
  • Render-blocking resources

Let’s look at each of these reasons and identify potential ways that Amazon can make its website load faster.

But before we do that, a quick word about our website - we are a free email alert service that sends out notification any time your website is loading very slowly (often due to heavy traffic, or poor scripts). If you have a website, consider setting up an alert so that you can fix issues before they become major. 

Bloated JavaScript files

Amazon uses a lot of JavaScript to run the website. However, loading them all from one source could slow up the performance of the website. Amazon can avoid this by splitting the code into smaller files. This way, you only load files that are necessary.

The Amazon website can be as much as 0.3 seconds faster by adopting this technique.

Absence of lazyloading

Images and videos are by far the most resource-intensive assets and take up a lot of bandwidth during the page-loading process. This can be a real problem on shopping websites since they typically include a lot of graphical content.

But here is the thing – a user who visits the website is not going to need all the images on the page to load. Instead, they only need those images on the top fold of the website to load. The rest can be ‘lazy-loaded’ – that is, they can be loaded after all the other critical components of the webpage have completed loading.

The Amazon homepage can load as much as 2.7 seconds faster if images were lazyloaded.

Unnecessarily large image files

Another common problem that users face – especially when they access the website while on the move – is having to load unnecessarily large image files that are not optimized for the mobile phone. Not everyone has access to WiFi at all times. Loading oversized product images is unnecessary.

According to the Lighthouse estimate, the Amazon website homepage can load 2.25 seconds faster if it made all the images more cellular-data-friendly.

Old Image formats

The Amazon website uses a lot of JPG and PNG files that are considered outdated and heavy for modern web use. Replacing them with WebP and AVIF files can save as much as 2.55 seconds from the page loading time.

Render-blocking resources

There are scripts on the Amazon website that needs to run first before they let the rest of the code be executed. The render-blocking resources issue can shave off around 1.05 seconds from the loading time for the Amazon website.

How do you avoid this? If the script is not critical, avoid having it in the <head> tag of your HTML code. But if you do need to have it there for some reason, make sure to include the defer or async attribute so that they do not block the loading of other resources.

Large DOM size

The Amazon website takes close to 7.4 seconds to evaluate all the scripts, parse them, compile, and render them. This can be minimized by minimizing the main-thread work.

They may also look at reducing the number of nodes in the DOM. In simpler terms, you need to make sure that the main HTML code is smaller and has fewer nodes. I have explained this in greater detail in this article about DOMContentLoaded.

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