#gzip #compression

Bandwidth optimization

Web servers use gzip to reduce the total amount of data transferred to clients. When a browser with gzip support sends a request, it adds “gzip” to its Accept-Encoding header. When the web server receives the request, it generates the response as normal, then checks the Accept-Encoding header to determine how to encode the response. If the server supports gzip, it uses gzip to compress each resource. It then delivers the compressed copies of each resource with an added Content-Encoding header, specifying that the resource is encoded using gzip. The browser then decompresses the content into its original uncompressed version before rendering it to the user.

However, this comes at a cost. Compression is a CPU-intensive process, and the more you compress a file, the longer it takes. Because of this, gzip offers a range of compression levels from 1 to 9; 1 offers the fastest compression speed but at a lower ratio, and 9 offers the highest compression ratio but at a lower speed. The gzip application uses level 6 by default, favoring higher compression over speed. Nginx, on the other hand, uses level 1, favoring higher speeds over file size savings.

https://www.pingdom.com/blog/can-gzip-compression-really-improve-web-performance/