They add emphasis to the ~san suffix and the first person pronounboku, because normally Youta uses sessha as first person pronoun, and calls other people by ~dono, both things that otaku do, upon learning that Kaoru isn't an otaku, he switches to speaking like a normal person.
haa... はぁ・・・ *sigh*
kakyuu-teki sumiyaka ni... 可及的速やかに・・・ As quickly as possible...