my pc
nvidia geforce gt740m with 2gb dedicated vram
RAM : 4gb ddr3
i3-3217u 1.8ghz,3mb L3 cahe
it's possible for work mario galaxy 2 on full speed
I seriously doubt it because of the low clock speed of your CPU. You might want to try rendering at 1.5x internal resolution and enable the FPS counter to see how you do. Native resolution would be faster but will look hideous. Also turn off vsync and if the screen tear bothers you as much as it bothers me, then just make sure you are running with the Aero theme (if on Windows 7).
Your CPU isn't very great and you may get CPU bottlenecks. Grab the latest dev build
https://dolphin-emu.org/download/ (4.0-5190 as of writing) for the best experience possible