fast but unresponsive modem connection

[Jon <jmd000@myrealbox.com>]

I connect to the internet using a good modem & phone line. The
connection is reliable, and fast for a 56k modem.

My problem is this: say I am downloading a file already. Then I want to
check my POP3 server at the same time - it'll work, but it will take an
~extremely~ long time, so long that I want to pause/resume the file
download just to get on and off the email server in a normal length of
time.

So, the connection is responsive when nothing else is going on. And
there's nothing wrong with the transfer speeds. But if there is already
a webpage loading or whatever, anything else goes really slowly. I never
noticed this much of an effect on Windows and I don't think it's my
imagination.

'MTU size' comes to mind but I don't know anything about it. What can I
do?


Thanks in advance,
Jon.