I did a major remodel and some of the faucets have good water flow, but many have suboptimal water flow. My plumber says it is the plumbing fixtures, not the pipes (all redone in copper) or any installation issues. I don't know how to assess this and I don't know how to fix it (short of replacing many faucets if that is the issue). I am in California that has low flow requirements. Most of the faucets are from Newport Brass.

Any thoughts? If there is good (very good - and it is a different brand product) flow in one tub then can I assume that it is truly the faucets on the others (especially the other ones right near by)?