I don't have a test case for this bug, I'm afraid, but here's what I'm
seeing:

I read mail and news while travelling by using a putty client on my
phone.  I ssh in to my home machine and have a screen there with an
Emacs running Gnus.

It seems like that when Emacs is doing network stuff (web/news), the
cursor is displayed momentarily visually at the first point in the
screen.  Then it's displayed momentarily at the first point in the echo
area.  Sometimes this repeats a few times.

Often the entire connection hangs while it's doing this -- I'm unable to
exit the screen for instance, so I suspect that Emacs is actually moving
the cursor back and forth between these two positions more rapidly than
my phone is able to display.

Once while this was happening, I got an SMS from my telco warning me
about large roaming data costs, which further points to this behaviour
generating a lot of data over the wire.

I have no idea how to start debugging this problem, but it's easily
reproducible for me.

It started happening about half a year ago.  Does anybody have any
inkling what might be causing this problem?  If not, I can try to see if
I can find a way to debug this.

Uhmn...

Oh, here's an strace from me typing `n' (next article) in Gnus four
times.  The second and fourth time this cursor-moving behaviour was
triggered: