Yesterday I used MissionControl 0.15.1 on a Switch running firmware 22.1.0/Atmosphere 1.11.1 to play Crash Team Racing Nitro-Fueled and Marion Kart 8 Deluxe with 3x Dualshock 3 (PS3) controllers. It got heavy input lag, making both games unplayable.
But when I only use 1 Dualshock 3 and let the other 2 players use a pair of Joy-Cons and a knock-off Switch pro controller, there are no notable problems.
I remember playing 3-player CTR with 2 DS3's and one pair of Joy-Cons on another Switch was usable too.
Is it simply not possible to use too much DS3 controllers at the same time without heavy input lag?