Improving ASP.NET Session State database performance by reducing blocking

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On a recent consulting engagement, I was working with a client that had significant performance issues with their ASP.NET session state database. They had a combination of both large session state and a large number of concurrent sessions. They were regularly experiencing command timeouts on that database.
In my investigation, curiously I found that a DELETE statement was the culprit. I tracked it to the DeleteExpiredSessions stored procedure. Looking at it, it seems tame enough:
CREATE PROCEDURE DeleteExpiredSessions
AS
  DECLARE @now DATETIME
  SET @now = GETUTCDATE()

  DELETE ASPState..ASPStateTempSessions
  WHERE Expires < @now
  RETURN 0
GO
However, the problem is that as session size grows, each delete takes longer and as the number of sessions grows, this simple DELETE ends up causing substantial blocking. It was at the head of nearly every blocking chain. This proc is run every five minutes.
There is no need for this proc to do all the deletes in a single operation. I replaced it with one that does a series of individual deletes:
CREATE PROCEDURE dbo.DeleteExpiredSessions
AS
  DECLARE @now datetime
  SET @now = GETUTCDATE()

  CREATE TABLE #ExpiredSessions

  ( SessionID nvarchar(88) NOT NULL    PRIMARY KEY  )
  INSERT #ExpiredSessions (SessionID)

  SELECT SessionID
  FROM [ASPState_2_0].dbo.ASPStateTempSessions
  WHERE Expires < @now
  DECLARE SessionCursor CURSOR LOCAL FORWARD_ONLY READ_ONLY
  FOR SELECT SessionID FROM #ExpiredSessions ORDER BY CHECKSUM(NEWID())
  DECLARE @SessionID nvarchar(88)

  OPEN SessionCursor
  FETCH NEXT FROM SessionCursor INTO @SessionID
  WHILE @@FETCH_STATUS = 0 BEGIN
    DELETE FROM [ASPState_2_0].dbo.ASPStateTempSessions
      WHERE SessionID = @SessionID
    FETCH NEXT FROM SessionCursor INTO @SessionID
  END
  CLOSE SessionCursor
  DEALLOCATE SessionCursor
  DROP TABLE #ExpiredSessions
  RETURN 0
GO


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