Racing with a dodger
I am not sure that the dodger really slows you down noticably do to windage or anything like that. I think it is more of an impediment to crew work and steering (and that will vary from boat to boat and whether you race with spinacker or not. It is next to imposible to race with a spinacker with a dodger because the trimmer should be up at the weather shrouds to be able to see properly and the dodger would normally prevent that. The dodger is generally in the line of sight for trimmers and the helmsman and so makes it harder to do things. The easier something can be done on the race course the more likely that it will be done more often and more correctly.