Enable cache

Hi,
When i use http url to load pdf, it is delay for few seconds to load. and how to enable cache once we open a pdf file using http url from next time it should open even if we don't have internet connection.
Can anybody help me out in this?

delay few seconds, is expected in case of remote url..it depends on several factors (connection, pdf size, server status/configuration).
Cache, is not supported for security reasons.
you need to implement the cache behavior yourself.