A buddy of mine has a full machine shop in his garage and he taught me years ago that low drill speed with a lot of pressure cuts better and saves drill bits. The oil helps to keep the heat down. Also remember, if the bit starts singing, you are doing it wrong (and the bit is dull so it's too late).

Of course, drilling through wood is just the opposite - high drill speed and low pressure to reduce splintering and cracking (not apropo in this forum but nice to know).