Generally, if you're working on files over a network, you're only going to work as fast as the slowest part of the connection.
If your network is a 100Mbps connection (most common) there can be lots of lag when working with the files on the network servers. If it's a Gigabit (1000Mbps) connection between the servers and workstations you'll probably be going a lot faster, but depending on what you're doing with the files (how much photoshop, cleanup, modification, adjusting, etc) it will still be slower than if you were working on the files locally on the workstation you're working on.
The simplest solution would be to copy the image you're working on to the computer you're using at the time and do your work on it there. Then, once you're done modifying, adjusting, editing, adding mustaches to the principal, and enlarging the pecs of the jocks, you copy the files back into place on the server, preferably into a different directory so as not to overwrite the originals.
This will take the slowness and congestion of the network out of the equation.