Yes, having those variables not seen at compile time isn't an option, for the reason I already gave. My code is but one piece of a bigger project for which I have no control over what modules get loaded or what their content is. I'll admit to a lack of details on my situation but not of consistency in my answers...

Again, profile it.

Always a good advice. Profiling with NYTProf prior to my original post is how I detected the source of my issue.

Learning facts like that is part of the reason for reading the docs

Another great piece of advice. I quote perlvar myself in my post so I think I pass :)