Using Virtualbox 5.0 with Windows 8.1 as host and Ubuntu 14.04.2 as guest. It is extremely slow. I have tried
1) Increasing the RAM size
2) Used multiple processors in Systems->Processor tab (have IntelCore i7 processor)
3) Enabled 3D Acceleration in Display->Screen tab
4) Increased the video memory
5) Tried enabling/disabling Extended features in the settings
6) Also tried Ubuntu-15.04 (behavior remains the same)
Here's (Why does a Ubuntu guest in VirtualBox run very, very slowly?) from a user some time back.
The system is still slow...is there anything to be done in the BIOS? and i doubt it, as my windows is pretty fast. Any help appreciated! (Thanks!)