SQL Server stored procedure slows every execution - performance

Question

I've got a stored procedure which does many selects and updates with some cursors.
When I execute the procedure the first time, it takes about 30 seconds. Second execution takes about 1 minute. Third about 2 minutes.
Every execution slows the procedure. Now it takes about 10 minutes.
What is going wrong?
Variables:
declare #StatistikStatus nvarchar(100)
declare #SQL as nvarchar(MAX)
declare #Datum as nvarchar(50) --Datum im nvarchar Format
declare #Datumdatetime datetime --Datum im datetime Format
declare #tickethistorieID as uniqueidentifier
declare #id int --ID der Terminauswertung. Wird bei Einträgen benötigt, die pro Ticket mehrere Termine vereinbart haben.
declare #nextTermin datetime --Wird bei Einträgen benötigt, die pro Ticket mehrere Termine vereinbart haben.
declare #status nvarchar(100)
declare #statusdiff as nvarchar(100)
declare #vorStatus as nvarchar(100)
declare #lastid as int
declare #tickethistoriemerker nvarchar(40)
declare #statistikstatusmerker nvarchar(100)
DECLARE #TicketID uniqueidentifier
Sample cursor:
DECLARE C_TicketHistorie CURSOR FOR
SELECT
dbo.TicketHistorie.TicketID,dbo.TicketHistorie.Datum,dbo.tickethistorie.tickethistorieid
FROM
dbo.TicketHistorie INNER JOIN
dbo.Status ON dbo.TicketHistorie.NeueStatusID = dbo.Status.StatusID
INNER JOIN dbo.StatuszuStatistikStatus as s on s.status_ID = dbo.Status.statusid
INNER JOIN dbo.StatistikStatus as ss on s.bewertung_id = ss.id
WHERE
ss.id = 5 AND -- 5 = HNR Terminbestätigung
(dbo.Status.Name = N'Termin vereinbart')
AND ((YEAR(dbo.TicketHistorie.Datum) >= 2011 and day(dbo.TicketHistorie.Datum) >= 27 and month(dbo.TicketHistorie.Datum) >= 12)or YEAR(dbo.TicketHistorie.Datum) >= 2012)
ORDER BY TicketID,Datum asc
OPEN C_TicketHistorie;
FETCH NEXT FROM C_TicketHistorie into #TicketID,#Datumdatetime,#TickethistorieID
WHILE ##FETCH_STATUS = 0
BEGIN
--some inserts etc.
FETCH NEXT FROM C_TicketHistorie into #TicketID,#Datumdatetime,#TickethistorieID
END
CLOSE C_TicketHistorie
DEALLOCATE C_TicketHistorie
I've got 4 cursors.
And some dynamix SQL like this
SET #SQL ='UPDATE Statistik.dbo.terminauswertungab27122011 SET ['
SET #SQL =#SQL + #StatistikStatus+']='''
SET #SQL =#SQL + cast(#TicketHistorieID as NVARCHAR(36))+''''
SET #SQL =#SQL + ' WHERE ID = ' + cast(#ID as nvarchar) +' and ['+#StatistikStatus+'] IS NULL'
EXEC (#SQL)
I call the procedure using SSMS.
at the beginning of the stp i delete the table where the inserts goes into. Then iam doing the Inserts. the table rows are the same every execution

Answer 1

First off, change your cursor declaration to a more efficient cursor:
DECLARE C_TicketHistorie CURSOR
LOCAL STATIC FORWARD_ONLY READ_ONLY
FOR
Next, are you sure that you need a cursor for these operations? It seems that your update, for example, could be accomplished as a single set-based operation instead of a cursor and dynamic SQL, especially if you know the set of column names that could be indicated by #StatistikStatus (where is this determined, by the way?). Here is how you could generate a set-based dynamic SQL update in one swoop instead of a cursor:
DECLARE #sql NVARCHAR(MAX) = N'';
WITH x AS
(
SELECT
-- why only use aliases for the tables you don't reference often?
th.TicketID, th.Datum, th.tickethistorieid
FROM
dbo.TicketHistorie AS th
INNER JOIN dbo.Status AS st
ON th.NeueStatusID = st.StatusID
INNER JOIN dbo.StatuszuStatistikStatus as s
on s.status_ID = st.statusid
INNER JOIN dbo.StatistikStatus as ss
on s.bewertung_id = ss.id
WHERE
ss.id = 5 -- 5 = HNR Terminbestätigung
AND st.Name = N'Termin vereinbart'
-- be smarter about date range queries!
AND dbo.TicketHistorie.Datum >= '2011127'
)
SELECT #sql += N'UPDATE Statistik.dbo.terminauswertungab27122011 SET ['
+ #StatistikStatus+']='''
+ cast(#TicketHistorieID as NVARCHAR(36))+''''
+ ' WHERE ID = ' + cast(#ID as nvarchar) + ' -- nvarchar(WHAT)?
and ['+#StatistikStatus+'] IS NULL;';
Probably a lot more optimization possible here, but as the comments suggest, tough to do without more info.