My last comparisons with the active vs backdrop tiles setup are about 3 years old now, but back then actives were really slower on my setup, even on PC (I never had real gaming machines tho).
I think Actives come with a significant load compared to backdrops due to what Danny said, plus animation frame, animation direction, angle, scale x + y, strings, changeable RGB, changeable opacity. That's a lot of stuff to keep track of for a tile that just needs to sit around.
Actives can be very useful tho if you're able to scale them as collision blocks. Fusion does not burn a unifying collision mask on HWA... so for collision checks, in my experience, the tile count matters a lot more compared to backdrop vs actives.
In the end, I went with a setup that uses reasonable small backdrops for the cosmetics, and blocky large rectangles to construct a collision mask as simple as possible.
I dunno, I don't think it's a big deal either way, at least on PC. I've never used a single backdrop in my life, and I've never seen any performance problems due to that. I've hit performance walls over the years for various other reasons (eg. I've gone too heavy with shaders or particle effects or gigantic 4096x4096 background actives or poorly structured code), but besides that, I've never had a problem getting smooth framerates on PC, despite using active objects for absolutely everything. Backdrops are just way too limited for me to even consider using them, since you can't do anything to them in events.
All irrelevant if you want to use animated level tiles, and with PMO it handles jump through a differently to obstacles so you have to use actives for one of them and backdrops for the other.