Fair enough I guess. Had the same problem myself in the uni. I could rush and stutter or take it slow but 3x longer. If 30ppl have to wait it out then yeah, it's wasting everyone's time. If it's a small class with enough time then go for the slower version. Use this as an opportunity to condense the information in to as few words as possible, no fillers or long sentences. Employ visual aids such as graphs, animations, pics etc. Never repeat the same point. This is actually a very good skill to have even for non stutters because some people just drag on and on :)