cross apply xml query performs exponentially worse as xml document grows

Question

What I Have

I have a variable size XML document that needs to be parsed on MSSQL 2008 R2 that looks like this:

Answer 1

Adding an XML index did the trick. Now the 6,500 records that took 20 minutes to run takes < 4 seconds.

create table #temp (id int primary key, x xml)
create primary xml index idx_x on #temp (x)

insert into #temp (id, x)
values (1, '

  
    0.506543009706267
    -0.79500402346138
    0.0152649050024924
  
  
    0.366096802804087
    -0.386642801354842
    0.031671174184115
  
  
    0.883962036959074
    -0.781459993268713
    0.228442351572923
  

')

select c.value('(../@name)','varchar(5)') as item_name
      ,c.value('(@id)','uniqueidentifier') as field_id
      ,c.value('(@type)','int') as field_type
      ,c.value('(.)','nvarchar(15)') as field_value
from   #temp cross apply
       #temp.x.nodes('/data/item/field') as y(c)

drop table #temp