We recently noticed that with the ATLAS Multi Core application, there is a HUGE performance difference between the old and new version virtualbox, and this is especially obvious with big multi core (Core number >4 ).

As shown in this host with 12 Cores allocated to BOINC, the older version of virtualbox (4.2.16) uses almost 3 times of CPU time compared to the newer version(5.1.2) with the same kind of jobs.More results of other hosts from our database confirms this difference. And our database also shows around 7% of hosts still use older virtualbox(version