ShimmerCat implements Brotli by default for compression of static assets, which compared to gzip is well worth the substantial file size savings.
What is compression?
When a user hits your website a call is made to the 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.
Brotli compresses your webpages and objects 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 alread
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.
What are the alternatives?
The most common compression in use is Gzip