Dropping/Recreating Index vs Setting Disable/Enabled

Hi, I need to drop/create index for a very large volatile table(> 1 million rows) frequently to enhance performance. If the index has become inefficient, does disabling and enabling the index rebuild the entire index tree like what dropping and creating the index do or does it merely updates the index tree? If they behave differently, which of these two methods will give a better performance in terms of query optimization? Any help is appreciated. Regards, TM Chan