Our Hudson builds a .war file of about 100MB. Sending this artifact from the
slave to the master over Gbit ethernet takes about 2 or 3 minutes. Gbit
ethernet should do this in about 1 second theoreticly. Practicly scp takes
about 4 seconds to copy 100MB.

I made this testcase.
-> New freestyle build -> Add build step 'Execute Shell' -> enter 'dd if=/dev/
urandom of=this_is_big.bin bs=1M count=100' -> Archive artifacts
'this_is_big.bin' -> Schedule at slave -> dd takes about 45 seconds -> job
takes about 3 minutes.

ngrep shows me a lot of serialized java stuff, but very little effective data
is send per packet.

I'm using Hudson 1.300 for master and slave.
I hope people can reproduce and fix it.