Is it safe to put <configdirectory>/proc and <configdirectory>/lock on a tmpfs filesystem?

It's safe to put both of these in tmpfs, and since they're fairly busy it's a good idea for performance reasons. Further, nothing ever removes files from <configdirectory>/lock/, so it's probably a good idea in general to mount that on tmpfs such that a reboot will purge it. The Cyrus code will create all the necessary directory structure under <configdirectory>/lock on-demand.