I have a set of these. I use them to make plugs. I am drilling into face grain.
If they are smoking due to heat build-up I would not go faster, since that will generate even more heat.
The wood may have resins which are causing the burning. Try a test in another piece of scrap of different species, just to see if they cut the same.
You can try honing the cutting edges to ensure they are as sharp as you can get. Also may need to back off the drill several times to allow it to cool.
Plan "B" will be to get a different cutter. These Lee Valley cutters are designed to cut with less heat. I just purchased by first one, a 7/8in diameter and it does cut a lot easier than my set which looks like your set.
http://www.leevalley.com/US/Wood/page.aspx?p=42292&cat=1,180,42288&ap=1