Technical Support :
Taking a break from Cosmology@home
Posted 30 Aug 2017 by GARY
Hi pe, appreciate your contributions and sad but understand the decision to leave.
The performance issue you're describing is most likely this one, unfortunately caused by a bug in Virtualbox which is completely out of our control. As mentioned in the link, a partial workaround is to limit the number of cores used by the camb_boinc2docker app. If you leave at least one core completely idle, or even in use but crunching non-vbox apps, that should still keep your computer responsive.
Anyway, we will certainly post once that problem is solved on the VBox end.