Not having anything to test with, this is a possible alternative that converts your multi-statement tvf into an inline tvf. Test it out and compare it to what you already have (you may want to change the name to do some head to head comparisions).

drop function dbo.fDayCount;

go

CREATE FUNCTION [dbo].[fDayCount]

(

@WorkDate DATETIME

)

RETURNS @returntable TABLE

AS

return(

SELECT

workdate,

companyID

FROM

dbo.table1

INNER JOIN dbo.table2

ON table1.a = table2.a

WHERE

date = @date

AND companyid IN(select

ds.Item

from

dbo.config

cross apply dbo.DelimtedSplit8K(CompID,',') ds

where

configva = 'compidstring')

);

go