As I understand the nocopy boot command option.
The different sfs's are only loaded (layered) into the final layered operating filesystem.
The contents of the sfs stays on the drive.
Anything needed from them, is gotten by accessing the sfs, by reading it as needed, and putting that specific needed item from the sfs, into RAM to use.
So if something is later needed from one of the sfs's.
That needed item is read from the sfs and put into RAM to be used.
Computer runs slower, because time is used to read the sfs, find the item requested, and put that item into RAM.
Mainly the longer time it takes to read from the drive, (copy) move the requested item from the drive, and put it into RAM.
During booting process all the needed stuff to run the computer and end up with an operating Puppy.
Only what is needed is read from the sfs's and put into RAM.
This is the same as if you did a full install of Puppy, that will have no SFS files in the full install.
Everything stays on the drive until needed to be put into RAM to use.
A normal boot,
having the different sfs's load into RAM.
Eliminates the need to read from the drive, and move stuff into RAM.
The save file or folder always stays on the drive and has to be read from it, requested item moved into RAM to use.
The filesystem in the save is only layered into the operating filesystem, not loaded into RAM.