Two SSH Connections to Server, One Is Slow

I have a Redhat Linux Enterprise 3 server in Dallas hosted at The Planet
with unthrottled bandwidth on a 100 Mbps NIC. I recently switched from
DSL to Cable for my home connection, which is running Windows 2000.

Today I SSHed into the Linux server from home twice using different
account names.

On connection A I opened up emacs in X as a background process, and then
I ran a script that ran for about an hour and continually spit out alot
of stuff to the console.

On connection B I didn't run any programs.

While the script was running on connection A, there was a serious lag in
emacs that was opened on connection A so that typed characters would
take a few seconds to appear; however, there was no noticeable lag on
connection B.

Why would one SSH connection be slow and one not since both connections
were to/from the same two servers?