I use grade 25 bb's because they are only pennies more than lower spec bb's. Better performance?...probably not noticeable. I'm more concerned about preventing damage to the more expensive races in the hubs, BB's, and headsets. So when I routinely disassemble, clean, and grease and reassemble these parts I just throw out the old bb's and replace them with new ones. Many would view that as unecessary and wasteful, but that's what I do.