Your own hardware may be working wonderfully, but
it’s being strangled by bandwidth limitations
between you and the Web backbone. You should be able to make rough
estimates of the bandwidth you need by multiplying the number of
transactions per second by the number of bytes transferred (making
allowance for the substantial HTTP headers that go with each web
page). Having done that, check what is actually happening by using a
utility like ipfm from http://www.via.ecp.fr/~tibob/ipfm/:
HOST IN OUT TOTAL host1.domain.com 12345 6666684 6679029 host2.domain.com 1232314 12345 1244659 host3.domain.com 6645632 123 6645755 ...
Or use cricket (http://cricket.sourceforge.net/) to produce pretty graphs.