It is currently possible to efficiently transfer ArrayBuffers to and from WebWorkers using transferables. https://developer.mozilla.org/en-US/docs/Web/API/Transferable
https://developers.google.com/web/updates/2011/12/Transferable-Objects-Lightning-Fast?hl=en

In this way it might yield a responsiveness/apparent performance improvement to do compression and decompression on a separate thread. For some applications, (including my own,) this might be suitable.