Is it possible to write extension which could refuse to get certains files like .js, .css or images? When a webpage asks server to download images or any files, the extension should to refuse such files. I mean to speed up loading of the webpage… I am interested only about the DOM document and the other documents are unnecessary.
You can block requests with https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/webRequest.