When under load, give 503 aggressively for dirport requests without compression
Preliminary analysis of the parent ticket suggests that most of the problematic requests are coming from an aggressively non-tor sources. One reasonable thing we could do to disfavor them is to give a 503 to directory requests that don't request compression, either with a ".z" suffix or an Accept-Encoding list.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information