mounting a drive

I am seeking a better understanding of OS X.
so it is easy to drop to a terminal window and list a usb stick's directory using 'ls'

I am wondering about a NAS drive though.

I have a 1TB drive NAS (buffalo) on my network. I can easily connect to it via finder and 'connect to' using the network address. if I choose a rather large directory to view in finder, it can sometimes take up to 10 minutes to refresh the display of contents.

Does the /Volumes/mounted drive directory need to download all of the data into the directory to mount it or is it a sequential type read? the read used to be faster, but the NAS drive has gotten fuller and I still have half the drive space left on my mac. The mac in speaking is a macmini 1.1, 120gb, 2 gb ram. os 10.6.8?

It's just read/write I/O, but if your NAS is short of drive space, that may cause a slow down on its end (it's going to have to run some sort of OS, and a network file system stack).