Guest optimization tips for Ubuntu on VirtualBox [closed]
Solution 1:
Ubuntu's got a kernel meant explicitly for running in virtual machines; you might want to take a look at that. The package is called linux-virtual
.
Solution 2:
A very basic, but in my opinion often forgot, tip is to simple uninstall all the programs not needed - even the X graphical user interface (if you don't depend on it).
Like already mentioned: using the VM optimized kernel will normally give you a huge performance boost and is most of the times recommended.
If you need your VM for some special tasks only, try thinking about a window manager switch. Moving from Gnome to a more lightweight and ressource-friendly WM like XFCE, Fluxbox, etc. can lower the memory usage, too.