HELP - GAMING

[Greeat]

Hello, I am a Brazilian User VirtualBox my host is Windows 8 64-bit ... I started using VB to be using macros in games, more'm having some trouble with VB, I have installed on my virtual machine Windows 7 Ultmate 32bit installed all the requirements for the use of games in the virtual machine, the more open the game in question, the game screen is flashing up of to be using, but this losing FPS sharply since the time the game flashes on the screen. .. I wonder if there is any solution to this problem in my machine

settings
host-
Windows 8.1 64Bits
Graphic Card: RADEON HD 6770
Processor: Core i5-2400 3.10GHz
Memory: 12 GB

virtual Machine
Windows 7 32bits Ultmate
Memory: 3GB

Game: Aura Kingdom PTBR


I hope you have some solution to my problem of flashes on the game screen ... Thank you and I look a community response.