I noticed that some of my UserParameter values take a long time to be retrived. One example could be checking version of chef software, which was done by trivial:
UserParameter chef.version,chef-client -v
I found it took over 15 seconds on some machines (I use timeout 15).
It would be nice to set a threshold above which execution of parameter (user defined and build in) are logged (just like slow queries on MySQL), but not terminated yet.