But after you’ve completed the Anubis PoW challenge for a site, it remains valid for some amount of time.

So it’s not quite as horrible as it sounds.

I have setting up Anubis for my own sites on my todo list. And I wish more people did it too. I don’t really mind waiting a little bit extra every now and then before the page loads. What I do mind is ReCaptcha asking me to click all the pictures with buses in them etc. And especially when I have to do it several times over before it’s happy. I’d rather wait a minute for a page to load than to ever solve a ReCaptcha again, if given the choice.

That must be really low end then. I’ve never seen it complete in a timeframe that was slower than “I can’t even read the page before it redirects”

There's not an easy, perfect solution, for sure. Newer phones get faster, but spammer compute gets cheaper.

Some sort of decentralized trust web seems like another option, though less viable.