A read only mode will give quick access without the overhead of rewriting to disk. Alternatively, consider not deleting files when read, and instead double checking whether anything is altered the same way it is done in save_index now.
This allows for a read only access, but doesn't necessarily give a read only mode, which would speed up the process by eliminating all write checks. Also needs to eliminate cache+"Set" write.
A read only mode will give quick access without the overhead of rewriting to disk. Alternatively, consider not deleting files when read, and instead double checking whether anything is altered the same way it is done in save_index now.