As regards time-consuming, I tried http://thesaurus.com/browse/time-consuming for time-consuming but the results don't categorically pertain to time.
As concerns less time-consuming, I tried resesarching synonyms for productive (http://www.merriam-webster.com/thesaurus/productive) yet again, the results don't categorically pertain to time.
Examples upon request:
Inasmuch as it'd be overly time-consuming to Google each individually,
what are some less time-consuming ways to find bestselling French nonfiction (either originally written in or translated into French) which are available as audiobooks?