Those controls are extra loose, I'm playing on Android and there is a very noticable delay between moving the controls in a direction and your character actually going in that direction.
Super Ember Ushi Milk Bounce (On It Dayo) 2 Gaiden Hyper Arcade Action ZZZ Cup Edition & Knuckles » Comments
There’s momentum and acceleration on the character and that’s probably what you’re feeling. If you get the sonic speed upgrade, it actually bypasses momentum and acceleration.
Otherwise the touchscreen logic actively falls back to the controller logic that has a ~5% deadzone on the analogue stick.
You are right though. Compared to touch or controller input, keyboard does feel better.