>When testing extensions on the Apple homepage we can see that a dark mode extension called Dark Reader spends 25 seconds analyzing and adjusting images so that they better fit into a dark theme. As a result the page loads much more slowly, as we'll see later on.

Sums up my experience not only on Dark Reader but a lot of other Dark mode extension. To the point I simply give up and use some specific CSS extensions. ( However I still get a white screen flash and then turn dark with every refresh or page load, wonder if anyone has a solution to that ).

The same with Ad Block. I just use NextDNS now and it is so much better.