SQL Server 2016 uses less memory

Hi,

The restore of a database is running in SQL Server 2016 and it is very slow. Below are memory details

In Windows server 2012 R2, Task Manger > Performance > memory details are below

Memory in Use - 37 GB
Available Memory - 470 GB
Committed - 38/550 GB
Cached - 195 GB
Paged Pool - 917 MB
Non Paged Pool - 380 MB

Memory used by SQL Server 2016 - 25 GB

Please let us know why SQL Server 2016 is using very less memory ? if it uses more memory will the restore be fast ? Please advice.