For some reason I do not stutter when i'm giving a speech/presentation

For some reason I do not stutter when i'm giving a speech/presentation Hello guys, i've been stuttering since i was 5. My stuttering was really bad(would rate it 8/10) but during the years i improved a lot(mainly by not being under constant stress). When i talk to people i stutter usually on every 7th word or so, sometimes when i'm too excited or anxious i have to stop speaking for a while because i cannot pronounce a single word without stuttering. I mean this is all normal for now, but for some reason i do not stutter when i'm giving a speech, and i don't know why. I'm always anxious(just like everyone else), but for some reason when i start speaking, my anxious thoughts disappear, i become relaxed and stop stuttering. People have often complimented me saying that my speech was great because i looked so relaxed and i was 'radiating positive energy' . What do you think about this?