确定非键盘事件方法调用中的键盘状态

In a textbox.TextChanged event I want to prevent some specific (processor intensive) functionality from executing if a key is still held down. E.g. while the user is deleting large regions of text by holding down the delete key I want to prevent the code from firing if the delete key is still held down.In a textbox.TextChanged event I want to preven