Thanks for the hint with lazy loading – it helped a lot to activate that.
Also disabled right-clicked behaviour as you said.
Unfortunately I used some png-Files on the slides, they cannot be compressed too small apparently. But already tried that.
Wordpress was installed from the web hoster customer’s menu.
Have to say that I am using a multi site installation. Surely that does not help.
As I am merely using the site as an extension to my CV for an application, I think the changes will do the trick.
Thank you very much again!