Thanks for the feedback Tom. Yeah I tried it with and without .emacs and it was slow either way. Just as a test I booted into a 32 bit f20 install on the same machine/hard drive and yum updated it and everything worked fine-- nice and fast. The 64 bit install was configured exactly the same way as the 32 bit version with regard to installed packages, NFS mounts, Selinux disabled, etc, so I'm really at a loss as to what's going on.
Maybe I'll see if I can find something like truss on linux to see what's going on behind the scenes.
Cheers