A bit more from my side... Extract from a reply in a similar post:
Without additional licenses to enable FlashBackup or dedupe with Backup Accelerator, you can enable Multistreaming and break down Backup Selection into multiple streams - between 4 and 8 should give good performance without affecting restore speed too much.
It all depends on layout of filesystem - something like:
NEW_STREAM
X:\folder1\a*
X:\folder1\b*
X:\folder1\c*
.....
..
NEW_STREAM
X:\folder1\g*
X:\folder1\h*
X:\folder1\i*
.....
NEW_STREAM
X:\folder1\m*
X:\folder1\n*
X:\folder1\o*
.....
NEW_STREAM
X:\folder1\r*
X:\folder1\s*
X:\folder1\t*
......
etc..
Plus another post: https://www.veritas.com/community/forums/netbackup-multi-steam-backup#comment-6221771