PageSpeed: Enable compression
Reduce the size of files sent from your server to increase the speed to which they are transferred to the browser.
- Reduce sizes of pages by up to 70%
- Increase page speed
- Cost-benefit ratio: high
- Access needed to the .htaccess files or server administration files
How does your site score on this recommendation?
What is compression?
When a user hits your website a call is made to your server to deliver the requested files.
The bigger these files are the longer it's going to take for them to get to your browser and appear on the screen.
Gzip/Brotli compresses your webpages and style sheets before sending them over to the browser. This drastically reduces transfer time since the files are much smaller.
In terms of cost versus benefit, compression should be near the top of your page speed optimizations if you don't have it setup already.
How does it work?
Gzip/Brotli is actually a fairly simple idea that is extremely powerful when put to good use. Gzip/Brotli locates similar strings within a text file and replaces those strings temporarily to make the overall file size smaller.
The reason gzip/Brotli works so well in a web environment is because CSS files and HTML files use a lot of repeated text and have loads of whitespace. Since gzip/Brotli compresses common strings, this can reduce the size of pages and style sheets by up to 70%!
Gzip/Brotli has to be enabled on your webserver which is relatively straight forward.
When a browser visits a webserver it checks to see if the server has gzip/Brotli enabled and requests the webpage. If it's enabled it receives the gzip/Brotli file which is significantly smaller and if it isn't, it still receives the page, only the uncompressed version which is much larger.
Why is it important?
The main reason it is important is because it reduces the time it takes for a website to transfer the page files and style sheets which ultimately reduces the load time of your website.
How to enable
There are different methods of setting up gzip/Brotli compression depending on whether or not you've got an IIS or Apache server (or something else entirely).
Read our Lighthouse documentation to learn more about enabling text compression.