Backup Exec 2012 running very slow

Hi,

Lately i'm noticed that my symantec Backup Exec 2012 running very slow. Means that when i create backup job, the process to load the selection of the servers very slow, almost take 5 minutes to see the selection of the servers it self. In addition, to perform test credentials also very slow. I'm using SBE2012 since 4 months ago and the performance 4 months ago is good, not very slow if compare with current status. Here i attach the screenshot for reference. Kindly advise how to make SBE2012 can running properly without slowest issue.