When you say a performance hit, what exactly are you talking about?  What is occurring while the stored procedure is running?

And this is the other query:
DECLARE @startdate SMALLDATETIME;
SET @startdate = '2017-01-01';

SELECT
  [Date]               = .[DateKey]
  , [Plan Week]        = .[PlanningWeekNo]
  , [Plan Day of...

Looks like you are using SQL Server 2016, try this:
DECLARE @startdate SMALLDATETIME;
SET @startdate = '2017-01-01';

SELECT
  [Date]               = .[DateKey]
  , [Plan Week]        = .[PlanningWeekNo]
 ...

If the answer to my question is yes, then try this:
CREATE VIEW [dbo].[abc]
AS
SELECT
  rmt.Material,
  rmt.Material_Desc,
  rmt.Matl_Grp_Nbr,
  rmt.Matl_Grp_Desc,
  T4.Matl_Addl_Desc_1,
  T4.Matl_Addl_Desc_2,

Okay, the database [ABC] is on the linked server [xy] and the database [XYZ] is on the local server, correct?

You can find more info here; https://www.microsoft.com/en-us/sql-server/sql-server-2017-pricing

If you want to license the underlying hardware you need to use Enterprise Edition + Software Assurance, not Standard Edition.

I'll have to do some research, but not sure if there is anything that will work similarly in SQL Server 2005.  Plus, I don't have a SQL Server 2005 instance...

I...

Again, what do you mean by doesn't work.

One, what do you mean by doesn't work.
Two, without see the code really have no idea.