The Collaborative International Dictionary of English v.0.48:

Dawdler \Daw"dler\, n.
   One who wastes time in trifling employments; an idler; a
   trifler.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dawdler
    n 1: someone who takes more time than necessary; someone who
         lags behind [syn: dawdler, drone, laggard, lagger,
         trailer, poke]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "dawdler":
   clock watcher, dallier, dawdle, diddler, dillydallier, do-nothing,
   dolittle, doodler, drone, faineant, foot-dragger,
   gentleman of leisure, goldbrick, goldbricker, goof-off, idler,
   laggard, lie-abed, lingerer, loafer, loiterer, loller, lotus-eater,
   lounger, lubber, mope, moper, plodder, potterer, procrastinator,
   putterer, sleepyhead, slouch, sloucher, slow goer, slow-foot,
   slowbelly, slowpoke, slug, sluggard, snail, stick-in-the-mud,
   time killer, time waster, tortoise, trifler,
   waiter on Providence