1. One or more non-transitory computer-readable storage mediums storing one or more sequences of instructions for executing a virtualized web browser on a device, which when executed by one or more processors, cause: a host operating system receiving, from one of one or more virtual machines, updated state data relevant to performing a user-initiated action, wherein the updated state data includes one or more of: one or more cache files and web browser setting data, and wherein said one of said one or more virtual machines consults a first policy to determine whether to send said updated state data to said host operating system; said host operating system consulting a second policy to determine which, if any, of said one or more virtual machines should receive said updated state data based upon, at least in part, a set of responsibilities assigned to each of said one or more virtual machines, wherein said second policy indicates that the updated state data should be provided to only those virtual machines, of said set of one or more virtual machines, which have been assigned responsibilities to which the updated state data is pertinent; the host operating system providing said updated state data to at least one of said one or more virtual machines which does not currently possess said updated state data; after the host operating system provides said updated state data to said at least one of said one or more virtual machines and upon the virtualized web browser receiving an instruction, within the host operating system executing on said device, to display a web page, retrieving, from each of said one or more virtual machines executing on said device, rendered contents for a portion of the web page; and upon the virtualized web browser receiving the rendered contents from each of the one or more virtual machines, the virtualized web browser assembling the rendered contents and displaying the web page.