I'm trying to confirm an observation I've made while playing the game.

Heavier weapons, in general, appear to attack slower. I'm not talking about warhammers vs daggers mind you, I mean weapons within the same class. For example, an iron sword weighs about half as much as a daedric sword, and appears to attack much more quickly. Similarly, an iron dagger swings faster than a daedric dagger. And for bows, a 5lb longbow draws much faster than an 18lb Daedric bow.

Is there any truth to this or am i imagining things? I'm trying to find a formula for how attack speed is determined (so I can find the best balance for my playstyle), but have come up short. Does anyone have any information on this?

With bows, there's a definite difference: a longbow will draw about twice as quickly as a daedric bow. If you've done some heavy upgrading via smithing, it'll have higher overall damage output because of that (although its per-shot damage will still be lower, so the daedric one will be better for a stealth snipe).

Melee weapons don't seem to have this sort of variability according to the UESP, although there are a few specific weapons that have nonstandard swing speeds.