As soon as you have access to the full, decrypted data stream it's most probably possible to cache everything.

But :
The, for example, ccs style sheet file, can have a unique name - and won't be re used ever again, so it will get reloaded anyway.
The file creation date can be set to 'now' so the browser will request a fresh copy, even if the content didn't change at all.
etc etc .