I run a photo heavy blog, occasionally with 24-30 images per post. I size all images to the dimensions set in my theme and compress them manually to around 65% (or whatever suits the specific image).

A couple of years ago I tried the WebP format and it was a disaster! The new format often didn’t result in any smaller file sizes, no, some were larger files.

But since at the time not all browsers supported WebP images, the plugin created a “cache” directory that sat alongside my already large media library.

So soon my database doubled in size, which
a) exceeded my hosting account;
b) and of course doubled my back-ups in size, so they required more hosting resources to run and occasionally failed halfway through;
c) these backups logically also exceeded my off-site storage for them.

Was I able to see any speed improvement? No, not at all!

The opposite seem to happen because for every image there was a decision which one to include (or was it because the WebP cache wasn’t properly indexed and not sorted by post order?).

Needless to say: I don’t want to repeat this mistake!