Cancel a call to the repaint() method

Hi
I am developing a CAD application and am using a JPanel to display some heavy graphics. When the user draws a new object I have to repaint the JPanel to display the underlying drawing. The repaint method is called quite a no. of times, and the response of the software is very slow.
How can I cancel an incomplete call to the repaint() method of the JPanel if I get another request for repaint().
Also, is it possible that the underlying drawing on the JPanel remains undisturbed even if a new object(eg. line/circle etc.) is being drawn and erased repeatedly on it.
Thanks in advance.
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Amit Agarwal