I used the VirtualBox - version 4.3.28.xxxx and Fedora Linux 22.
The main reason was to test how fast it's the Fedora 22 over VirtualBox.
And the answer was just a few minutes.
My hardware come with NVIDIA video card Geforce 740M, CPU: 2117U -1.80Ghz and 4Gb RAM.
I used Fedora-Workstation-netinst-x86_64-22.iso.
This will take some time when you install because this will use the network to download all packages.
You need to set one new Linux os over Virtual Box and make this setting:
Load the Fedora .iso and start it with Show/Play button.
After that, if all packages are on your computer then the next step comes with unloading the .iso file and select the virtual drive.
This can be seen under Controler: SATA. Let all settings under Network: NAT.
Start it with Show button and you will see working well.
I like very much the new Virtual Box and Fedora also, because it's fast (~ 1 min) and I don't need to start another hardware to test my linux stuff.