APC and most other php opcode caches are able to cache files if they are php files and included as one.

This will mean format of cache files will need to change and all cache will need to be cleared.
Additional benefit is that no unserialize call is needed anymore.

Note: This should be taken together with larger cache system refactoring.
For instance classes could be used for cache files to make sure you can use class_exist( <name>, false ) to see if file has already been loaded (nice for compiled templates for instance).