Every standard language is characterized by a range of speech styles, which encompasses not just the segmental aspects but such paralinguistic features as the pace at which speakers habitually deliver their utterances. In this respect American English is unexceptionally variegated, even though most speakers fall into fairly narrow categories when it comes to pace of delivery. Typically, the truly idiosyncratic speaking styles are those that are categorized by speech mannerisms, including dialectal peculiarities in otherwise normative speech.
The qualification “ponderous” or “portentous” applies to speech that is so painfully slow when compared to general norms as to stand out as stylistically inappropriate regardless of the speaker’s predilections. Moreover, when the content is utterly trivial or plebeian, utterances delivered at a labored and gravid pace can only try an interlocutor’s patience and create the impression (among others) that the speaker has nothing to say. Those who speak at the same pace regardless of what they are saying run the risk of seeming dull and colorless.
Speaking a language is like playing a musical instrument. A gavotte played at a tempo appropriate to a dirge will not set anyone to dancing.