Backup Exec 2012: verify (from tape) is slow

Hi, an overage Rate is ~ 2862 MB/min. LTO5

For comparison, the overall backup for this tape drive (LTO5) is 1670 MB/MIN. for around 1.250 TB. Containing ~ 3M of files :)
LTO6 provides ~2.692 MB/MIN.

While I'm happy (well not really with ) with backup rates (turning AV off, results in even better MBs), I'm not happy with verification time, which takes considerable time to finish. Is there anything we can do to make it faster ?

Enc:
BE 2010 SP4, Windows 2008 R2.
Drives: LTO5: Hp Utrium 3000 SAS , LTO6 :HP StoreEver LTO-6 Ultrium 6250
Node-duplicationoption is selected.

I heard that it could be related to faulty SAS cable.Anyone having experience with that ?

Thanks in advance!

EDIT
Sorry, our BE version is 2012 SP4, not 2010 SP4