Yes, the lack of performance knowledge IS embarrasing.
I try to go over, with my FO's, manual W&B, to include MLW & MTOW calcs using QRH for lndg runway limits and climb limits and well as VAA to go over takeoff runway and climb limit weights and QRH V speeds. I also go over Bingo fuel calculations, holding calcs, the difference between "Inflight landing distance" and "Unfactored landing distance". Some roll thier eyes when I ask if they would like for me to go over it, but most really appreciate it.
As Captains, it's up to us to pick up where the training center falls short (or simply don't have time). It's also in our best interest to make sure the people sitting next to us know how to jump in and help with these calculations when things get busy.