Why Is Facebook Website So Slow? Here Are The Reasons

Facebook is perhaps the largest and most popular social media network. Facebook’s parent company Meta also owns other popular social media platforms like Instagram and WhatsApp.

A speed report from Lighthouse paints a rather grim picture and scores Facebook website 4.7 seconds on the speed index (SI), and 64 on Performance.

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

  • Bloated JavaScript files
  • Unnecessarily large image files
  • Old Image formats
  • Render-blocking resources
  • Large DOM size

Let’s look at each of these reasons and identify potential ways that Facebook 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

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

The Facebook website can be as much as 1.2 seconds faster by adopting this technique.

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 Facebook website homepage can load 0.6 seconds faster if it made all the images more cellular-data-friendly.

Old Image formats

The Facebook website uses a lot of JPG and PNG files that are considered outdated and heavy for modern web use.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 0.6 seconds from the page loading time.

Render-blocking resources

There are scripts on the Facebook website that need to run first before they let the rest of the code be executed. The render-blocking resources issue can shave off around 0.15 seconds from the loading time for the Facebook 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 Facebook website takes close to 3.3 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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