The SUBJ_ALL_CAPS regexp rule uses exponential backoff, which can be a problem
if you have a Perl version that doesn't handle such stuff gracefully.  In
general, though, because of the regexp's suboptimal behavior in the first place,
it ought to be avoided and replaced with an eval test.  I already had a
discussion about this with Charlie Watts <cewatts@frontier.net> on the list. 
I'll attach my patches, which I already submitted to the list, in an appended
document.