I’ve done something like this, with RSS feeds. Read !meta@rss.ponder.cat to see the existing communities, and how to add a feed to an existing community.
The concern about spam is real. A lot of these exist, for example one for Hacker News and a whole instance for Reddit, and a lot of people including myself don’t like those. I agree with you that it’s a good idea but it’s necessary to be careful that it remains a useful seed of content and not an overwhelming spew.
Much less than seconds. The naive algorithm is a loop to 4096 doing one integer divide on each iteration. I think the limiting factor is going to be the memory access to load the code from main memory, so you can say the whole thing can basically be done within the length of time of one memory fetch.
I still think it’s a significant development. Doing a toy problem on a radically different hardware platform that has the potential to scale up and tackle real-scale problems orders of magnitude more efficiently than the existing architecture is progress. I’m just saying that saying “break RSA” is pure clickbait.