You mean increasing your graphic card performace? You can easily buy a better graphic card if you want to? There are ways to make use of your graphics card so it function better but increasing the graphic card performance i have never heard before. An i7 processor can surely help you with that...
Is there any external graphics card i can get for my laptop
There's a way to increase graphic card performance and it's call 'Overclock'... It increase the frequency of your graphic card or processor to boost graphic handling like playing high graphic usage games.
In return, overclock cancel your warranty automatically for your graphic card and will wear out sooner. It should be use by someone who knows the risk of overclock and able to cope whatever will happen to your computer.