efficiency improvements
efficiency improvements

git-svn-id: f7ac333d3f078fc2d8ea384f67eaebefe0f0ab5a@7021 a8237c23-d22b-0410-ac1a-db40f18c2caa

benedictpaten/jobTree,BD2KGenomics/slugflow,BD2KGenomics/toil-old,cooketho/jobTree,BD2KGenomics/slugflow,harvardinformatics/jobTree