In absolute terms, yes, it does suck.
But for me, hell I just want some portable 1P Classic Sonic (specifically S3&K), so I'm satisfied. And again, the lag occurs when there are numerous items on screen. Zones like Marble (1), Chemical Plant (2), and Hill Top (2) will be a-okay, whereas the heavier parts of Star Light (1), Casino Night (2), and Death Egg (K) will see their share of lag.
BTW, Sonic 1's not as hard to complete as I thought. I only had to retry Emerald 5 once.
And getting there was easier than I had remembered; a number of acts have 2 or 3 10-Ring Monitors near the end in hidden areas (lookin' at you, Star Light).