Releasing RAM is slowly done in SuperDome Server

[HamidAranji]

Hi

I have a server with 8T physical memory(RAM).

When I stop my SQL Server service, the service want deallocate it's memory and take it back to Windows.

But this routine happen with very very low speed, approximately 2 gigabyte per second, and total deallocation happen in about 1~2 hours!!!

Its very bad and I need to tune it. I have a question, Is it relative to my server RAM speed. or is relative to SQL Server configuration? 

My SQL Server memory operations speed also is slow in other routines not only when releasing the memory, even when i start or use the database service i have very low speed.

windows : 2016 

SQL Server : 2016 Enterprise Sp1

Thank you for any help.