Why is my query so slow? - asp.net

Question

I try to tune my query but I have no idea what I can change:
A screenshot of both tables: http://abload.de/image.php?img=1plkyg.jpg
The relation is: 1 UserPM (a Private Message) has 1 Sender (User, SenderID -> User.SenderID) and 1 Recipient (User, RecipientID -> User.UserID) and 1 User has X UserPMs as Recipient and X UserPMs as Sender.
The intial load takes around 200ms, it only takes the first 20 rows and display them. After this is displayed a JavaScript PageMethod gets the GetAllPMsAsReciepient method and loads the rest of the data
this GetAllPMsAsReciepient method takes around 4.5 to 5.0 seconds each time to run on around 250 rows
My code:
public static List<UserPM> GetAllPMsAsReciepient(Guid userID)
{
using (RPGDataContext dc = new RPGDataContext())
{
DateTime dt = DateTime.Now;
DataLoadOptions options = new DataLoadOptions();
//options.LoadWith<UserPM>(a => a.User);
options.LoadWith<UserPM>(a => a.User1);
dc.LoadOptions = options;
List<UserPM> pm = (
from a in dc.UserPMs
where a.RecieverID == userID
&& !a.IsDeletedRec
orderby a.Timestamp descending select a
).ToList();
TimeSpan ts = DateTime.Now - dt;
System.Diagnostics.Debug.WriteLine(ts.Seconds + "." + ts.Milliseconds);
return pm;
}
}
I have no idea how to tune this Query, I mean 250 PMs are nothing at all, on other inboxes on other websites I got around 5000 or something and it doesn't need a single second to load...
I try to set Indexes on Timestamp to reduce the Orderby time but nothing happend so far.
Any ideas here?
EDIT
I try to reproduce it on LinqPad:
Without the DataLoadOptions, in LinqPad the query needs 300ms, with DataLoadOptions around 1 Second.
So, that means:
I could save around 60% of the time, If I can avoid to load the User-table within this query, but how?
Why Linqpad needs only 1 second on the same connection, from the same computer, where my code is need 4.5-5.0 seconds?
Here is the execution plan: http://abload.de/image.php?img=54rjwq.jpg
Here is the SQL Linqpad gives me:
SELECT [t0].[PMID], [t0].[Text], [t0].[RecieverID], [t0].[SenderID], [t0].[Title], [t0].[Timestamp], [t0].[IsDeletedRec], [t0].[IsRead], [t0].[IsDeletedSender], [t0].[IsAnswered], [t1].[UserID], [t1].[Username], [t1].[Password], [t1].[Email], [t1].[RegisterDate], [t1].[LastLogin], [t1].[RegisterIP], [t1].[RefreshPing], [t1].[Admin], [t1].[IsDeleted], [t1].[DeletedFrom], [t1].[IsBanned], [t1].[BannedReason], [t1].[BannedFrom], [t1].[BannedAt], [t1].[NowPlay], [t1].[AcceptAGB], [t1].[AcceptRules], [t1].[MainProfile], [t1].[SetShowHTMLEditorInRPGPosts], [t1].[Age], [t1].[SetIsAgePublic], [t1].[City], [t1].[SetIsCityShown], [t1].[Verified], [t1].[Design], [t1].[SetRPGCountPublic], [t1].[SetLastLoginPublic], [t1].[SetRegisterDatePublic], [t1].[SetGBActive], [t1].[Gender], [t1].[IsGenderVisible], [t1].[OnlinelistHidden], [t1].[Birthday], [t1].[SetIsMenuHideable], [t1].[SetColorButtons], [t1].[SetIsAboutMePublic], [t1].[Name], [t1].[SetIsNamePublic], [t1].[ContactAnimexx], [t1].[ContactRPGLand], [t1].[ContactSkype], [t1].[ContactICQ], [t1].[ContactDeviantArt], [t1].[ContactFacebook], [t1].[ContactTwitter], [t1].[ContactTumblr], [t1].[IsContactAnimexxPublic], [t1].[IsContactRPGLandPublic], [t1].[IsContactSkypePublic], [t1].[IsContactICQPublic], [t1].[IsContactDeviantArtPublic], [t1].[IsContactFacebookPublic], [t1].[IsContactTwitterPublic], [t1].[IsContactTumblrPublic], [t1].[IsAdult], [t1].[IsShoutboxVisible], [t1].[Notification], [t1].[ShowTutorial], [t1].[MainProfilePreview], [t1].[SetSound], [t1].[EmailNotification], [t1].[UsernameOld], [t1].[UsernameChangeDate]
FROM [UserPM] AS [t0]
INNER JOIN [User] AS [t1] ON [t1].[UserID] = [t0].[RecieverID]
WHERE ([t0].[RecieverID] = #p0) AND (NOT ([t0].[IsDeletedRec] = 1))
ORDER BY [t0].[Timestamp] DESC

Answer 1

If you want to get rid of the LoadWith, you can select your field explicitly :
public static List<Tuple<UserPM, User> > GetAllPMsAsReciepient(Guid userID)
{
using (var dataContext = new RPGDataContext())
{
return (
from a in dataContext.UserPMs
where a.RecieverID == userID
&& !a.IsDeletedRec
orderby a.Timestamp descending
select Tuple.Create(a, a.User1)
).ToList();
}
}

Answer 2

I found a solution:
At first it seems that with the DataLoadOptions is something not okay, at second its not clever to load a table with 30 Coloumns when you only need 1.
To Solve this, I make a view which covers all nececeery fields and of course the join.
It reduces the time from 5.0 seconds to 230ms!