1. In a networked computer system, a method of responding locally to requests for file metadata without downloading the file from a remote location, the method comprising: (a) receiving, by a streaming service at a local machine located at a user, from a remote machine, (i) a directory structure comprising a plurality of executable files representing an application program stored by the remote machine, and (ii) metadata associated with each of the plurality of files comprising the stored application program; (b) storing the directory structure and the metadata in an isolation environment on the local machine, the isolation environment comprising an application isolation layer and a user isolation layer; (c) intercepting, by a file system filter driver executing on the local machine, at least one request from an application executing on the local machine within the context of an isolation scope provided by the application isolation layer or user isolation layer to access metadata associated with one of the plurality of files; (d) responding to the at least one request using the metadata stored in the isolation environment; (e) receiving, by the streaming service at the local machine, a request to enumerate files associated with the metadata; (f) responding, by the streaming service at the local machine, to the request using the stored directory structure; (g) receiving, by the streaming service at the local machine, one of the plurality of executable files representing the application program; and (h) beginning execution, at the local machine, of the application program before receiving the rest of the plurality of executable files comprising the stored application program.