Oh, one other problem. The referenced (R) and dirty (D) bits are only updated in leaf nodes. I strongly suspect that any performance you gain here will be more

Oh, one other problem. The referenced (R) and dirty (D) bits are only updated in leaf nodes. I strongly suspect that any performance you gain here will be more than consumed by OS software needing to scan all the leaf nodes for these bits. If you update non-leaf nodes, then the OS can use those to avoid checking many of the leaf nodes.