marginal

marginal adj.  1. Extremely small.  "A marginal increase in
   {core} can decrease {GC} time drastically."  In everyday
   terms, this means that it is a lot easier to clean off your desk if
   you have a spare place to put some of the junk while you sort
   through it.  2. Of extremely small merit.  "This proposed new
   feature seems rather marginal to me."  3. Of extremely small
   probability of {win}ning.  "The power supply was rather
   marginal anyway; no wonder it fried."