Adjusting Isight webcam settings on Imac 24" 2009

So ive tried out several webcam programs to adjust the Isight camera settings, but most of them dont work with different apps.

I bought Iglasses, wich is supposed to be one of the best. Its good, it works great, it has many features and the computer recognizes it as an own source, wich means you can use it on almost all kinda programs and websites that requres webcam.

But the problem is, when ever i use it on skype, the whole computer slows down. It´s like Iglasses uses to much CPU or something, wich slows down the whole computer, and the FPS is low compared to the isight, wich makes it laggy.

Do i need a better computer or whats the deal?

Is there any lightweight program where you can adjust the basic settings on the Isight webcam?

I got an Imac 2009model 24" Intel based 2.93Ghz, 8GB ram Nvidia geforce 256mb GT120