Mountain Lion slow to find computers on network

I'm on a University network and we have several computers that are networked in our set of buildings. It used to be that when I opened up the finder window the list of "Shared" would have several computers listed in it as well as an "All" selection. This no longer happens under ML. So I have to open up the Network option in Finder. When I do this it takes ML several minutes to "find" the other networked computers and populates the list one computer at a time. It does the same things for the different workgroups. In Lion this list would come up very quickly and I wouldn't have to wait around for the list to populate. Is this a common problem in ML or is there a way that I can fix this? This is happening on my 2008 Alum. Macbook running 10.8

Thanks