[RESOLVED] Optimize very slow UPDATE

[jcis]

I have this Update at work and I need to optimize it.

It's terribly slow because it's done in a subquery at field level with complicated conditions.
Does anybody know any way to rewrite this to make run faster?

UPDATE #POS SET SaldoDespuesEvento = (
		  SELECT  SUM(Importe) 
			FROM  #POS CTACTE2
		   WHERE  CTACTE2.CodComitente = #POS.CodComitente  
		     AND  CTACTE2.CodMoneda = #POS.CodMoneda
		     AND  CTACTE2.EstaAnulado = 0 
		     AND  (  
					DATEDIFF(day, CTACTE2.FechaLiquidacion, #POS.FechaLiquidacion) > 0 
					OR   (
							DATEDIFF(day, CTACTE2.FechaLiquidacion, #POS.FechaLiquidacion) = 0 
				 			AND  (	
				 					#POS.CodCtaCorrienteMon >= CTACTE2.CodCtaCorrienteMon
				 				  )
				 		 )
				   )
		  ) 
WHERE #POS.EstaAnulado = 0
  AND #POS.EsSaldoAnterior = 0