SQL - combine 2 string lists, Sql Server

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create function [dbo].[delimitedsplit8K] (
      @pstring varchar(8000)
    , @pdelimiter char(1)
  )
returns table with schemabinding as
 return
  with e1(N) as (
    select 1 union all select 1 union all select 1 union all 
    select 1 union all select 1 union all select 1 union all 
    select 1 union all select 1 union all select 1 union all select 1
  )
  , e2(N) as (select 1 from e1 a, e1 b)
  , e4(N) as (select 1 from e2 a, e2 b)
  , ctetally(N) as (
    select top (isnull(datalength(@pstring),0)) 
      row_number() over (order by (select null)) from e4
  )
  , ctestart(N1) as (
    select 1 union all
    select t.N+1 from ctetally t where substring(@pstring,t.N,1) = @pdelimiter
  )
  , ctelen(N1,L1) as (
    select s.N1,
      isnull(nullif(charindex(@pdelimiter,@pstring,s.N1),0)-s.N1,8000)
    from ctestart s
  )
 select itemnumber = row_number() over(order by l.N1)
      , item       = substring(@pstring, l.N1, l.L1)
   from ctelen l
;
go

declare @a varchar(100); set @a = 'a,b,c,d,e';
declare @b varchar(100); set @b = '1,2,3,4,5';

select stuff((
    select ','+a.Item+b.Item
    from [dbo].[delimitedsplit8K](@a,',') a
      inner join dbo.[delimitedsplit8K](@b,',') b
        on a.ItemNumber = b.ItemNumber
      for xml path (''), type).value('.','nvarchar(max)')
  ,1,1,'')

View schema
Execution time: 0,02 sec, rows selected: 3, rows affected: 0, absolute service time: 0,19 sec