Should I enable GZIP compression for WebP images?

Question

Is it still relevant to enable gzip compression after compressed the WebP images..?

In my case I use compression middleware for express.

Answer 1

Yahoo suggests against it:

Image and PDF files should not be gzipped because they are already compressed. Trying to gzip them not only wastes CPU but can potentially increase file sizes.

https://developer.yahoo.com/performance/rules.html

And this may be helpful: https://webmasters.stackexchange.com/questions/8382/gzipped-images-is-it-worth

Answer 2

Is it still relevant to enable gzip compression after compressed the WebP images..?

Yes.

The compression middleware never compressed images to begin with (by default), because most image formats already implement compression.

It only compresses responses for the following mime types:

• text/*
• */*+json
• */*+text
• */*+xml

(and possibly other formats if their "compressibility" is known, see the compressible documentation for more details)

Converting images to WebP doesn't make a difference on how it works, and the abovementioned mime types are still good candidates to apply compression to.