Exchange 2010 dag backup running slow

HI,

            1)Exchange server details

            windows server 2008 R2 enterprise edition service pack1

             Exchange 2010 build no 14.03.0195.001

              Netbackup version 7.5.0.7

              2) My exchange server backup  is running very slow . Last week they ugraded the exchange patch and now backup is running at at the speed of 400 kb\s. earlier it was 10000kb\s on an average

Regards,

Sachin Pangal