In many cases... using an add-on (like
@truonglv Image Optimizer) will improve that... it's just one more area where XF itself is failing. WebP is NOT the answer some claim. Not all sites will be served by WebP... but ALL sites would benefit from image optimization being a core part of XF. Granted... some of those shared hosting users may not be able to avail themselves of it, but that happens and they can always move into a better hosting environment if needed.... but there are many that don't suffer that limitation.
I use an add-on for images.... and here is a perfect example of HOW XF could improve itself.
View attachment 291128
I think a 50% optimization display ability should be WELL noticeable to users (and admins that are paying for the space to store those images) ... but we continue to worry about "how can we develop a new style engine/format" or how we can "benefit developers". The concern of bringing items to the fore that benefit what drives any forum (the actual USERS) takes a back seat it appears.
It remains one more simple example of where XF developers have stepped off the train of what benefits their license holders (and those license holders members) and to what benefits the 3rd party developers. Not everybody has unlimited funds to throw at outside developers.