I have thought about this too. Probably not specific for every civ, and not as extreme as halved research time, but I think that every leader trait could be linked to a number of techs (not necessarily all techs, and not necessarily only one trait per tech). If you possess a certain trait, say, financial, you will be able to research techs like Pottery, Banking, Corporation, etc., a bit faster. If you are spiritual, all the religious techs would come faster. Organized - Code of laws, Communism, Civil service. Industrious - Masonry, Metal casting, Industrialism. And on and on.