when opened admin tab the symantec manager become very slow & custom scan

Hello,

1- have symantec 12.1 when try open admin tab and select server

the it become very very slow it take more than 15 min to open next page

but when open another tab  working fast.

2- how to enable custom scan in symantec endpoint
i have only 2 scan (active scan & full scan) i want use custom scan if possible.

thanks in advance