Yoshi's Island has a touch of slowdown as well on a few of the busy levels on world 3 but I'm fairly certain there was a touch of that in the OG game but it's been years since I've played Yoshi's on real hardware and recall it being one that often causes issues with emulation
I was referring to Mario World, not Yoshi's Island. Never been bothered by it on Yoshi's Island; as you say, I probably remember it always being there. Perhaps it's always been there on Mario World too, but it seems really apparent on the Switch. The first couple of levels of Forest of Illusion are some good examples. Still really enjoying it though.
Aye, that's why I said "as well" in my post, I only cleared the first world in Mario World so I'll have to see about the stages later on in the game, it's not like the Switch isn't perfectly capable of emulating pretty much everything up to GC with ease considering that has been done on the chinese variant of the shield hardware but still might be Nintendo just getting the kinks outta the emulator they've gone with.
Link to the past chucked up a tiny bit of slowdown in a boss fight for me but it was pretty much identical to the SNES version of the fight where I remember always getting a touch of slowdown there too.
Gotta say though.... I've been playing almost nothing except for these SNES games for the last few days, they really hit it outta the park with some of the titles they've gone with, really worth the 20e for the year sub in these if you ask me, legit... if Yoshi's Island and Link to the Past were put on the eshop as a 2 games for 20e deal I would have bought them so this has me well pleased for the next year lol.