Virtualization Speed Concerns

Let me start by saying I've never posted here before so if any of these issues have been solved already please send me the link to those threads.
I know how help forums work and I'm a bit under-experienced in this so this can hopefully point me in the right direction.

I recently purchased a computer tower from a friend of mine that I'm messing around with
Specs: Intel Core i5 CPU 750 @ 2.67ghz x 4
8GB DDR3 Ram
1TB internal HDD
Gallium 0.4 on AMD RV770

Now here's the problem I'm having;

I'm running Ubuntu 14.04 LTS on this tower as my main OS

I'm using VirtualBox to virtualize Windows 7 Ultimate 64bit
The tower is more powerful than my previous computer (iMac Intel Core 2 Duo 2.6ghz, 4 GB DDR2 Ram, 2TB internal, and whatever graphics card Apple used in late 2008 for the $1500 model)
I expected this thing to run incredibly fast by comparison and while the main OS is fine, my virtualized OS is seriously lacking.

I've used virtual machines before and I know it's much different than a hardwired configuration, but it should still be able to run at a normal operating speed.
I have Windows 7 configured at about half my computers power (2 cores, 4gb ram) which should essentially be as efficient as my mac was
It's taking a long time to load, I've recently started noticing "trailing" i think is the word, where the mouse leaves littles ghosts all along the page.


Is there something I'm doing wrong, is there something I'm not doing?

Any input at all is appreciated, thanks for the help