'Memory upgrade in SQL Server database

I am running a .NET based application with SQL Server 2014. The total memory of the database server is 128 GB and out of that, 84 GB has been allocated to SQL Server.

Now there is a slowness in accessing the data and the application vendor claiming that this is an issue with the memory we have allocated. They are claiming like after 64 GB, SQL Server will use additional memory only if we allocate 128 GB and the extra memory ( 84 -64 = 20 GB) is now useless and can not be used by SQL Server.

I am a bit confused here. Can anyone experience with .NET and SQL Server help me with this?



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source