Linked Server using ODBC too slow
Why not just use the SQLNCLI10 provider? Are you required to use MSDASQL?

Here is a sp_addlinkedserver script adding a linked server named ServerST that points to ServerAR.

EXEC master.dbo.sp_addlinkedserver @server = N'ServerST', @srvproduct=N'ServerST', 
    @provider=N'SQLNCLI10', @datasrc=N'ServerAR'


Update 19/082014

Download SQL Query Stress Tool to compare performance of both SQL Servers, ServerST and ServerAR. 



Scripting out your existing Linked Server

This will also include any specially defined parameters such as collation and time out configurations.