C# – EXTREMELY Poor LINQ Query Performance When Using Skip/Take for Paging

I need to query records from a DB2 database using LINQ. I have entities that have been generated from the DB schema and am attempting to perform a LINQ query using Skip and Take. The underlying table has like 25 columns and maybe a million records. When I execute the query without the "Skip()" it takes approximately .508 milliseconds to complete. When I include Skip() it takes close to 30 seconds. Big difference.

Can anyone tell me why this is happening?

UPDATE: Here is the LINQ query I am using.

var x = 30;

var results = context.ASSET_T
.OrderBy(c => c.ASSET_ID)
.Skip(x)
.Take(x)
.ToList();

UPDATE: So I just tried updating the query so that I only return a single column, ASSET_ID. When I only return that one column the query WITH the Skip() only takes .256 milliseconds.

var x = 30;

var results = context.ASSET_T
.OrderBy(c => c.ASSET_ID)
.Skip(x)
.Take(x)
.Select(c => c.ASSET_ID)
.ToList();

If I include any additional columns then the query execution time increases DRAMATICALLY.

The query below for example takes 10 seconds to execute.

var x = 30;

var results = context.ASSET_T
.OrderBy(c => c.ASSET_ID)
.Skip(x)
.Take(x)
.Select(c => new {
                 ASSET_ID = c.ASSET_ID,
                 ASSET_TYP = c.ASSET_TYP
                 ASSET_DESC = c.ASSET_DESC
                 })
.ToList();

UPDATE: I have now discovered that there are issues (perhaps index-related) with the columns in the table I am trying to query. As I mentioned above, when I execute a query that only returns the ASSET_ID column it only takes .256 milliseconds. If I try to execute a query that ONLY returns ASSET_DESC or a query that ONLY returns ASSET_TYP then the query execution time jumps to around 9 seconds.

Would this indicate that those other columns are not currently being indexed?

UPDATE: I have added the SQL output from the above LINQ query.

SELECT 
Project1.C1 AS C1, 
Project1.ASSET_ID AS ASSET_ID, 
Project1.ASSET_TYP AS ASSET_TYP, 
Project1.ASSET_DESC AS ASSET_DESC
FROM ( SELECT Project1.ASSET_ID AS ASSET_ID, Project1.ASSET_TYP AS ASSET_TYP, Project1.ASSET_DESC AS ASSET_DESC, Project1.C1 AS C1, row_number() OVER (ORDER BY Project1.ASSET_ID ASC, Project1.ASSET_TYP ASC, Project1.ASSET_DESC ASC) AS row_number
  FROM ( SELECT 
    Extent1.ASSET_ID AS ASSET_ID, 
    Extent1.ASSET_TYP AS ASSET_TYP, 
    Extent1.ASSET_DESC AS ASSET_DESC, 
    CAST(1 AS int) AS C1
    FROM MYDB.ASSET_T AS Extent1
  )  AS Project1
)  AS Project1
WHERE Project1.row_number > 1
ORDER BY Project1.ASSET_ID ASC, Project1.ASSET_TYP ASC, Project1.ASSET_DESC ASC FETCH  FIRST 31 ROWS ONLY