For instance a professional Perl programmer would be someone who makes a living by programming in Perl.

For example I am a professional Perl programmer. So is dragonchild. I do not see dragonchild's comments about his being a professional or the behaviour of professionals to be in any way childish. Rather they are precise and accurate.

As he said, decent professional Perl programmers do not as a rule waste their time and their employer's money by rewriting dbms or DBI without a very good reason. Generally no such reason exists. Certainly performance does not qualify. If Perl with those tools available to it does not perform adequately to the job, then the odds are excellent that the bottleneck is not in those tools. Look to your algorithm, data structures, and failing all else your language. (Good professional Perl programmers will tell their employers to use something else when ploughing ahead with Perl would be unwise.)

Professional Perl programmers who waste resources in reinventing good available wheels are generally liabilities for their employers. Competently run companies seek to eliminate such liabilities. Usual techniques include training, moving them into different roles, and firing.

Awareness of this fact is one of the reasons that decent professional Perl programmers who wish to remain so (which is most of them) behave as dragonchild describes.