Talk:List of light aircraft carriers by upgraded maximum stats/@comment-26399913-20150910163707/@comment-26988710-20150910165244

Engine power. Bigger ships can carry larger, more powerful engines. It's really that simple.

Looking at Wikipedia, the fastest of the "Slow" (in-game) CVLs was Ryuuhou at 26.5 knots. The slowest fleet carrier was Kaga at 28 knots; all of the other CVs have a listed speed over 30 knots.