First of all, brianL is correct, you will not get optimum performance if you are running Linux "inside of" Windows. You will get the best performance by doing a full, native install to your hard drive, and installing the correct drivers for your video card (if required).
Second, please understand that Farmville uses the Adobe Flash Player. Flash is a proprietary, "closed source" product of the Adobe Corporation. Flash is not "open source" and is not considered part of the "Linux ecosystem." There is nothing that Ubuntu/Linux developers can do to improve your Flash experience, since Adobe does not share their trade-secret source code. If Flash is running poorly on your computer then you should contact Adobe Corp for help with their product.
Make sure that your computer meets the minimum hardware requirements for Ubuntu: https://help.ubuntu.com/community/In...emRequirements
PLUS the minimum requirements for Adobe Flash: https://www.adobe.com/products/flash...ech-specs.html
ALSO NOTE that Adobe has discontinued support for Flash in Linux as of 11.2. There is no guarantee Flash games like Farmville will play well in future Linux releases, and some gurus believe there are security/privacy concerns. If Farmville is your main criteria for choosing an operating system, I recommend you stick with Windows, because Adobe dedicates the majority of their research and development to supporting Windows (not Linux).