As a part of NGA we're going to use Shared Workers at the application launch, but it seems it takes too much time to start Shared Worker. See measurements we've made with raptor [1] (it also includes a benchmarking app). Essentially "coldlaunch.window__service-created" performance mark is created once we called SharedWorker.port.start() and "coldlaunch.shared-worker-service__file parsed" is performance mark that is called as the first statement in Shared Worker js file. So the time between these two performance marks is around ~250ms. So the question here is can we improve that number? [1] https://github.com/azasypkin/sw-tests#06.08.2015

Dupe of 1191339?

You definitely know better than me, if the "slow" part is the same for Service and Shared workers, than yes it's a dupe :) Also we can keep it open until we get something landed in bug 1191339 so that I can re-check once again and close/dupe it then.