Why do you think that burning a CD would adversely affect your system? I'm just curious as to why you think that would do that.
But, as Horndude said, it wont. I burn at LEAST 1 dvd a day, and my computer runs flawlessly. While it is burning, performance will be adversely affected because your computer is using nearly all of it's resources. But as soon as it finishes, your system will run as normal.