All week we've had issues with the site being up and down. There's been a tremendous amount of traffic to various pages, many of them old. Lots of redirects, and lots of volumes (hundreds or thousands of requests/sec). It seems like someone scanning archive.org and then hitting us from their various points.
We have put some blocks in NginX for older redirects, many of which don't really exist anymore as new pages. We are also blocking the Profile\Followers page, which is getting requested constantly.
Hopefully this will help, but right not we've been under some sort of attack or incredible bot scan.