When playing games on a portable system, it's important to keep in mind the limitations of that computing platform. Because you are limited by space and power requirements, there are numerous performance issues that you may see, such as graphical errors, crashes, lag and latency, or disconnects. There are, however, a number of things that you can do to alleviate some of the issues, as well as increase performance.

The first thing that you can do is to make sure that you have the most updated version of DirectX. This will ensure that your Windows® Operating System is running with the most up to date security and performance extensions. This can be downloaded from http://www.microsoft.com in the Downloads section, or by visiting this link: http://www.microsoft.com/windows/directx/default.aspx

If that does not help performance, try following the steps in  this article.

If those steps do not help, it's quite possible that your video card is working as intended. In order to keep the card from overheating and causing damage to your system, the graphic chipset drivers for portable systems, by design, will downgrade the performance of your video card as it gets pushed to its limits. It is also best to keep your laptop plugged in rather than working off of the battery power, as the system will downgrade its overall performance to best utilize battery power and to try and alleviate heat related issues.