json stream filter

Hi! first post on the list, so please bare with me ;-) we are handling a lot of cache files in our apps and use json to persist those contents on the filesystem, because it seems to be the fastest possible way to read/write files with PHP. Since I discovered stream-filters, http://www.php.net/manual/en/filters.php, we use those also for base64 encoding files before sending them over the wire, which preserves a lot of memory and allows even bigger files. Would it make sense to also have a native stream filter for fileformats like JSON, to get maximum performance for reading/writing those (and also to be able to write big files)? Thanks, Markus