Gzip compression means compressing a webpage in order to make it smaller. This will result in the server transferring smaller files to the visitor’s browser and will therefore improve the site speed. Gzip compression can be implemented in different ways, the best ways are to use mod_deflate or mod_gzip.
If Gzip is activated, the load of the server (i.e. the CPU usage) will increase. The positive effect of enabling Gzip however, is higher than the increase in the CPU usage. Gzip compression saves data traffic (smaller amounts of data is sent from the server to the visitor). Gzip will therefore also improve the site speed and the server will have less open connections (pages are loaded faster by the users, which will lower the amount of open connections).
This Gzip compression test will show if a page is compressed or not. It will show the original file size (without compression) and the file size with compression. It also shows the percentage saved regarding the page size.