To compare the two ways of finding files, pretend you can't remember where
the X configuration file XF86Config resides.

$ locate XF86Config
This should be pretty fast. You'll get a list of filenames that contain
XF86Config, something like this:

/etc/X11/XF86Config

/usr/X11R6/lib/X11/XF86Config

/usr/X11R6/lib/X11/XF86Config.eg

/usr/X11R6/man/man5/XF86Config.5x.gz

Now try the find command:

$ find / -name XF86Config
You will hear a lot of disk activity, and this will take a lot longer.
Results will look something like this:

/etc/X11/XF86Config

/usr/X11R6/lib/X11/XF86Config

find: /var/spool/cron/atjobs: Permission denied

find: /var/spool/cron/atspool: Permission denied

find: /var/lib/xdm/authdir: Permission denied