Fast SQLServer vs. slow(??) dotNet

Question

Hi,

I need your help. My problem is (probably) slow dotNet connection to Ms SQL Server.

I have dotNet application working at IIS v.6 and connected to Ms Sql 2005 base. Base contains storage procedure called WSWyswietlNag.

When I test this procedure in Sql Server Management Studio, procedure works fast.

When I connect to SQL Server from dotNet Application, procedure works very, very slow.

I don't understand this phenomenon.

Below is table generated from SQL Profiler. 

EventClass	ApplicationName	CPU	Duration	Error	UserId	Reads	RowCounts	TextData	Writes
10	.Net SqlClient Data Provider	24329	25624636	0	sa	144935	9	exec WSWyswietlNag @IDNaglowk=0,@Typ=N' ',@Lok=0,@IDKont=0,@IDKateg=0, @DataRejOd = 'Sep 15 2010 12:00:00:000AM',@DataRejDo='Oct 6 2010 12:00:00:000AM',@Nazwa=N'BRAK'	0
12	Microsoft SQL Server Management Studio - Query	63	73398	0	sa	16802	11	exec WSWyswietlNag @IDNaglowk=0,@Typ=N' ',@Lok=0,@IDKont=0,@IDKateg=0, @DataRejOd = 'Sep 15 2010 12:00:00:000AM',@DataRejDo='Oct 6 2010 12:00:00:000AM',@Nazwa=N'BRAK'	0

Same procedure, same parameters, different aplication only.

Environment: dotNet 3.0, in application to connect I used SqlDataSource.

What you think about this problem, what happened? Where is problem?

Thank you for each advice.

Wojciech