virtualbox.org

I would ask the tails folks since you say that older versions do not have this issue as well as other guests you use.

just tried tails 2.10. it did load the cpu to 100% for a little while, then back down to 0% and near that while using it. tails is going through an overhaul, so you might want to try the beta of 3.0, which is based on debian 9.

tails is meant for booting from usb. if you intend to run it from virtual machines, you probably want https://www.whonix.org/

I checked and tails version 2.10 uses Version 5.1.8 r111374 '5.1.8_Debian' guest additions which is newer ( and not the official build either ) than the version of VirtualBox you are using ( 5.0.32 ) and that can cause problems. While you can often run older guest additions you should never run newer ones as the host code has change a lot and using new additions will try to use it and it will not be there.

I will try to download and test run tails 2.10, but my dev box is running the latest and greatest from SVN and will not usually show this kind of issue.

Carmageddon wrote:as I was trying to drag-and-drop files onto the guest. The drop failed (the files didn't show up in the guest) and now the process is running at 100%. So this is probably a bug either in VBox or GA

I believe it's actually the difference between the GA versions and the main VirtualBox application. I've seen that happening in other guests as well. That, and shared folders fail to work if the GAs are not matching the VirtualBox version.

OK I finished my test. While it uses 100% of a processor during its long boot, it settles down to using no more that any other machine I test. See host information below.