Image is quite heavy in web traffic. it is about 53% whole web traffic. 

It is important to make sure loading image won‘t be a slow & bad experience to your user. 

There is a rearch showing that 

83% redictopm om file size using the MozJPEG Encoder https://youtu.be/0-3GBgRg9ow

You can use online tool to resize or format your image: https://squoosh.app/editor

[Web] About image: MozJPEG