Massive host slowdown during host packet capture

[charger]

Host OS: Ubuntu 9.04, but also confirmed on Ubuntu 9.10

Initial setup: Two linux (Ubuntu 9.04) VMs which have NICs bridged with an interface on the host

If I run a packet capture on the bridged interface, all of the running VMs start doing massive amounts of disk I/O, resulting in massive slowdown. Doing the same thing with VMWare does _not_ result in massive slowdown.

I did some testing earlier today, and found that I experience the slowdown regardless of the traffic being sent from the VMs. That is to say, having the VMs running caused a slowdown during packet capture whereas having no VMs running and having the VBox modules unloaded did not cause a slowdown