I use the pictures in slider in 1920x550 resolution, which I think is correct. I get a bad speed test and lighthouse test witch state that the images aren’t ‘Properly sized images’. An example of one of the pics ( https://i1.wp.com/www.caersbart.be/wp-content/uploads/2019/09/New-Project3.jpg?fit=1920%2C550&ssl=1&resize=1920%2C550 )
Also the slider makes the website shift (CLS), a way to work around this?
The problems are mainly for mobile visitors… the score there is really bad.
Hey there
Well, there is no other option than trying images with different size, however im not sure if this fixes your problem, I’ve seen similar reports from other users but at the end they did not make any changes
not clearly understand your message about website shift, what do you mean here?
‘Your posts and pages should output images that are the correct size for their containers to ensure visitors aren’t loading up unnecessarily large images - particularly for mobile users.’ is the message.
I compressed the files already but because of the size 1920x550 the slider still is heavy to load. Above that the slider element makes the web page unexpected shifting while the page is still downloading. Google will take Cumulative Layout Shift in account from 2021. I wondered if there is a solution?
Hi there
Yes, I understand, unfortunately, there is no solution for this problem yet, this will require theme update, I will report this problem but can’t say when exactly it gets fixed
Sorry for this incontinence 
