If the game usus IGT, are emulator runners allowed to use turbo? I think it would make runs much smoothier, in case it doesn't give the runner any advantage apart from real time

Im afraid this cant be allowed at this time. I do understand the convinience of that, however - it would be a bit tricky to check for sudden (abuse) of fast forward usage within the run and while its true that the game uses IGT for the end-time, the way IGT is calculated is done with the ingame frames, this means using the fast-forward function could potentially introduce frame skipping within the emulator and corrupt the times- though this hasent been checked yet but the fast forward function within duckduck is known to be kind of "maybe working"

And i try to streamline rules with our friends over at Dino2 and they have similar rules to turbo / cpu clockspeed for similar reasons.