I have a problem with doing things too slowly, too, but I think for different reasons. I eat slower than anyone I know, read slower, and always got behind on schoolwork and on the job. But it's not because I daydream. It's because I'm too much of a perfectionist and always try to get stuff done exactly right. I've learned ways to get around a lot of my problems with perfectionism, but there are certain things I haven't been able to fix (like reading too slowly). I don't really have any advice for you, sorry. Daydreaming has never really been a problem for me.
In science, ideology tends to corrupt; absolute ideology [corrupts] absolutely" - Robert Nisbet