Parachute cord for d-loop? pretty huge cord...

Yes I do tie my own D's. Only real tricks I use: don't put the 'love knots' around the string going the same way (helps prevent the D-loop from coming loose, and walking around the string), and once you have your proper length, fire the ends of the cord and press them perpendicularly against a knife blade to 'flange' the end. That will help it from backing out of the knot. Also a really good idea to serve them in.

What release are you using that's chewing up D's that badly? I don't know that I've ever HAD to replace a D-loop. I replace mine when I replace my string every season or so (depending on how much I've shot), I don't take the old one off, I just tie on a new one.