Thx for the condom review - never tried performa, guess I won't need to now
But it does sound like your bro is sensitive in both directions: sensitive to stimulation, and sensitive to chemicals designed to slow him down ... probably a good thing actually, as that gives you MUCH more control and you should be able to ride him as long as you like, finishing when and how you like.
Here's a suggestion:- practice wanking, aiming to last more than 5 min / 10 min / 15 min / 20 min / etc ...
More advanced suggestion:-
practice meditation - especially mindfulness, or breath counting
also practice directing and controlling the girl, and telling her how to move (a WG will be MUCH more amenable to this than a typical GF)
Have you tried multiple Qs? Second and third times will be longer ...
SO much better than chemicals and drugs.