In El Goonish Shive, Noah is quieter than most, but the dude can flounce and produce sparkles at will.
The eponymous character of Hanna Is Not a Boy's Name. Complete with Gender-Blender Name, natch. Notably, he is seen in an official guest strip making a face more commonly seen onSpongebob Squarepants ("FREEEEEE"), doesn't narrate the comic because he's too hyper, and has a Tall, Dark, and Snarky sidekick/Heterosexual Life Partner who does narrate (and is more than One Head Taller than Hanna). Hanna is not quite 5'3", has almost-fluorescent red hair, often dresses fairly colourfully, is quite the Motor Mouth, and is Older Than He Looks: as his bio says, he's "best described as an overly enthusiastic, obnoxious child in the body of a twenty four year old man." Except not exactly the body of a twenty four year old man, because he looks so young that nobody ever believes he's an adult.
Kazuki from Kenshiro no Tabi, who upon imbibing triple-sweetened strawberry-milk released enough energy to create a nuclear explosion.
Rocky from Lackadaisy. A skinny sugar addict smartmouth, Rocky's boundless energy combined with poor impulse control regularly gets him into trouble.
Rudy from Rain is upbeat, effeminate and one of the younger members of the cast.
Taisei from Sakana does fit the "hyperactive", "cheerful", and "loud" part, but he's not exactly small.
T-Bob from Something*Positive, described in an early bio as "the living embodiment of caffeine."
Eunchan from Weak Hero is often chipper, constantly runs his mouth, yells a lot, and makes silly gestures while fighting random thugs he finds on the street.