According to the Addison-Wesley LaserWriter Reference Manual (ISBN
#0-201-19258-6), Chapter 2, page 46:
"When the PostScript interpreter encounters the input /Palatino findfont,
it first searches the FontDirectory (in memory), then searches the disk
file system for the file named fonts/Palatino. If that search succeeds,
PostScript executes the file, thereby loading it into virtual memory and
registering the name Palatino in the FontDirectory."
Therefore, whenever the LaserWriter must find a font to use, it must search ALL
available fonts -- starting from its own memory, then going to any attached
hard disks -- to locate the proper font. It then must download it, as if from
the system, for it to be available for use. With a directory of over 400
fonts, the search and download take a great deal of extra time.