[tor-relays] High processor usage - just curious

[tor]

> If anyone wants to disable directory document caching, they can set:
> DirPort 0
> DirCache 0

This results in the following log entry:

  ​[warn] DirCache is disabled and we are configured as a relay. This may disqualify us from becoming a guard in the future.

​That's a bit vague. What's that about? Will disabling the DirCache affect the Guard flag (today)?