Is this a remotely hosted solution, or do you have direct network access to the servers hosting Dynamics?

While it's helpful to post your code, we clearly don't have all of it (e.g. dbo.erf()), and you haven't mentioned what kind of performance you are actually getting, other than...

Take the GO out of the middle of your code.   You can't have a stored procedure extend beyond a batch terminator.  There's no alternative.

I suspect there's an all math way to do it, but take a look at the following, which illustrates the process somewhat:
DECLARE @TIME AS time = GETDATE();
DECLARE @TIME_2...

Oops!   Messed up the syntax.   Here's the corrected version:
DECLARE @BD AS varchar(40);
DECLARE @myobrano AS int = NULL;
DECLARE @sql AS nvarchar(max);

SELECT @BD = 'databasename.dbo';
PRINT @BD;

Ideally, post the execution plan as a .sqlplan file.   What kind of JOINs are we talking about?  INNER ? OUTER ? APPLY?   Are the tables indexed?   What are the indexes?  ...

And just what are you hoping to accomplish by doing that?   It will happen on the same machine that the SQL Agent is running on, assuming that MS Access is...