So I'll just add this check to block.populate(), which makes it simple and basically free. If this isn't called then standard database checks would take over. I tested this last month (without this locktime aspect) and it was a nice little boost, but this will be a big boost, because it eliminates 9% of confirmation with no tradeoff. And I almost overlooked it. I was going to disable the block.populate() call so that we would get prevout.tx metadata necessary for caching!