high utilization during backup operation

I am running Netware 5.1 on a Compaq server with an external Compaq SDLT, using BackupExec 8.5. Whenever the backup software goes to do any operation, backup,restore, erase,etc, the processor utilization goes up to 75% and the server basically won’tdo anything until the backup software is finished. All the software on Novell and BackupExec has been updated with no change. The hardware is also on the latest patches and versions. This is becoming more of a problem especially when doing a full erase or backup. Any ideas out there? Thanks.