To selectively profile during only a portion of the code, invoke like this:

$ NYTPROF=start=no perl -d:NYTProf t/load.t -v

Then inside t/load.t add the following directives which tell Devel::NYTProf to start and stop profiling:

DB::enable_profile();
... ## profile this section
DB::finish_profile();

Add use Devel::NYTProf; in either the test file or in the module.