LSS: Integrity for directories and special files

Hopes that this security can be disabled in situations where you are managing bazillion of small files, like objects files on a compiler server farm...
Also, when your file manager opens your 500 Mbytes video file to display the first image as the icon, is the cryptographic hash of the whole file checked, or just the beginning of the file?
I have directories with *a lot of* ten to hundred of Mbytes video files, and there is no point in reading all that content in memory just to display their icon.