Hi! I have vbox 2.2.4 on ubuntu 9.04 host with ubuntu 9.04 guest (both server edition).
I have nic1 type bridged with bridgeadapter tap1, joined to a bridge br0, and the INTEL gigabit networks emulation on the virtualbox machine.
also on br0 i have a REAL eth0.
I tested with iperf on the real machine with another real machine in the same network and i got 990megabits/second, and i feel it is OK for a gigabit NIC, but when i test the internal net, from the vbox guest to the host i got only 400megabits/second. I feel that slow.
I tested with some TCP tunning, changing parameters, like window size, read memory and so, but none of them has shown almost any improvement.
Also i tested all the nic types that vbox can emulate, and all of them are the same speed more or less, from 370mbps to 410mbps.
I tried with ethtool, setting speed for both host and guest, on br0 and on tap1 without any improvement.
Do you know if i need something more?
PS: i don't have guest additions on the vbox, because i don't use graphical mode.