OpenChess

To calculate mobility, I need to loop over every enemy piece (the mobility for the moving side is already calculated by the quiscence search) which slows down my NPS from 17mil to 13mil. I can't figure out a good way to incrementally update sliding piece's attack maps. Is there a good way to do that, or some other way to make it more efficient?

Do you use bitboard or some kind of array representation? If you use bitboard, you might look at Olithink. His evaluation mostly relies on mobility.