If I'm reading this correctly ("a single homepage load of http://garryslist.org http://garryslist.org downloads 6.42 MB across 169 requests"), the test harnesse

If I'm reading this correctly ("a single homepage load of http://garryslist.org http://garryslist.org downloads 6.42 MB across 169 requests"), the test harnesses were being downloaded by end users. They weren't being installed as devDependencies.