The Collaborative International Dictionary of English v.0.48:

Expeditious \Ex`pe*di"tious\, a.
   Possessed of, or characterized by, expedition, or efficiency
   and rapidity in action; performed with, or acting with,
   expedition; quick; having celerity; speedily; as, an
   expeditious march or messenger. -- Ex`pe*di"tious*ly, adv.
   -- Ex`pe*di"tious*ness, n.

   Syn: Prompt; ready; speedy; alert. See Prompt.
        [1913 Webster]

WordNet (r) 3.0 (2006):

expeditious
    adj 1: marked by speed and efficiency

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "expeditious":
   agile, alacritous, alert, apt, breakneck, brisk, cursory, dashing,
   decisive, diligent, dispatchful, double-quick, eagle-winged,
   effective, effectual, efficacious, efficient, express, fast,
   festinate, feverish, fleet, flying, furious, galloping,
   hair-trigger, hasty, headlong, hurried, hustling, immediate,
   instant, instantaneous, last-minute, light of heel, light-footed,
   lively, mercurial, nimble, nimble-footed, on the spot, passing,
   precipitate, prompt, punctual, quick, quick as lightning,
   quick as thought, rapid, ready, reckless, running, sharp,
   slap-bang, slapdash, smart, snap, snappy, spanking, speedy, spry,
   summary, superficial, swift, urgent, winged