autoplay speed weird

Been noticing autoplay speeds on some games are all over the place lately. Even with turbo or quickspin, a few reels still drag, while other sessions absolutely fly. Doesn’t seem to match up to advertised speed settings. Wondering if the game’s underlying math or maybe even the server traffic is making a difference, or if it’s just on my end somehow. I’ve tested on a few different browsers and devices but still no pattern.

Anyone else get these odd fluctuations? Is there some reason the same slot has totally different speeds day to day?