I've used DBIx::Profile a lot with Oracle and never seen this error. Maybe you should report it to the author of the module. It should be easy enough to ignore those lines with something like grep -v implementor for now.

As for Devel::DProf, it doesn't really work in scripts that fork unless you do some tweaking (like the mod_perl-specific Apache::DProf does). You could look at the technique on this node for using the debugger with forking scripts and see if that works for you. DProf uses the same hooks as the debugger.