Many file systems are designed for very big systems. Embedded systems rarely need a directory depth of 1024 directories or maximum filename length of 1800 characters. Memory can be saved if the correct file systems are used with the appropriate options (compare msdos/minixfs/ext2fs/reiserfs...). Many file-systems have options to reduce the number of inodes provided or reduce filename length but keep in mind that every restriction on the file system (DOS 8.3 filename length or mkfs.minix -n14 giving you 14-character maximum filename length) is paid for by having to be careful of file conversions when moving files around (notably, msdos-fs is a real limitation), this easily can lead to hard-to-detect side-effects.