Seems to me like you are expecting a faster EXPORT , in turn the performance.

Would you post the parfile , which you are using to export the full DB ???

Genarally Huge Buffer value makes the export faster as well.

Ditect=Y , will ceratinly improve the speed of export , by bypassing the SQL communication Layer. But it is having some issues...

And its advisable to have the export dump file on a separate disk , where there is less or no I/O activity...