Akainu has no speed feats of note only reaction feats that are fairly impressive. Regardless, Baraggan has both the ability to dilate time and slow everything to a near stand still with himself being unaffected, and he can release respira which rapidly decays everything it touches including energy. I'll admit Akainu could stomp most of the Espada but Baraggan is his plateau. In the end he was only beaten by using his own power against him when Kido master Hacchi teleported his rapidly aging arm inside of Baraggan and this causing Baraggan to die from his own power. Akainu can't do such a thing.