4.3 Compress Your Files

Every file will take up a certain amount of room on a server’s hard drive, and this data will need to be sent across the wire to each visitor. Doing so will consume resources, but by using compression algorithms you can shrink each file to make its journey less impactful.

Criteria

Server-side Compression: If using a CMS, install an applicable plugin to enable on-the-fly server-side compression, such as Brotli or GZIP. Otherwise, use the provided server configuration files to include and tweak the performance-related features to the requirements.
Media Compression: Compress your various images, fonts, audio, and video; by reducing the quality and offering different resolutions / dimensions (sizes) before uploading to a server or content management system.

Impact

High

Effort

Low

Benefits

Social Equity:
Reduced reliance on a high-speed connection (which in many locations is unavailable).
Accessibility:
People with accessibility needs are disproportionately affected by poverty and lower levels of income and thereby are more likely to be unable to afford either a high speed or the high cost of data plans found on cellular networks and satellite providers.
Performance:
Reduced data consumption (with a slight increase in visitor CPU decompression with server-side techniques).
Economic:
Reduced data transfer allows for savings for individuals on a monitored data plan.

GRI

materials: Low
energy: Low
water: Low
emissions: Low

Example

Code:

Accept-Encoding: zstd, gzip, br, deflate

HTTP compression headers can be used to control the response.

Resources

View the Guideline