I have written a stored procedure that, yesterday, typically completed in under a second. Today, it takes about 18 seconds. I ran into the problem yesterday as well, and it seemed to be solved by DROPing and re-CREATEing the stored procedure. Today, that trick doesn't appear to be working. :(

Interestingly, if I copy the body of the stored procedure and execute it as a straightforward query it completes quickly. It seems to be the fact that it's a stored procedure that's slowing it down...!

Does anyone know what the problem might be? I've searched for answers, but often they recommend running it through Query Analyser, but I don't have have it - I'm using SQL Server 2008 Express for now.

The stored procedure is as follows;

ALTER PROCEDURE [dbo].[spGetPOIs]
@lat1 float,
@lon1 float,
@lat2 float,
@lon2 float,
@minLOD tinyint, 
@maxLOD tinyint,
@exact bit
AS
BEGIN
-- Create the query rectangle as a polygon
DECLARE @bounds geography;
SET @bounds = dbo.fnGetRectangleGeographyFromLatLons(@lat1, @lon1, @lat2, @lon2);

-- Perform the selection
if (@exact = 0)
BEGIN
    SELECT [ID], [Name], [Type], [Data], [MinLOD], [MaxLOD], [Location].[Lat] AS [Latitude], [Location].[Long] AS [Longitude], [SourceID]
    FROM [POIs]
    WHERE
        NOT ((@maxLOD < [MinLOD]) OR (@minLOD > [MaxLOD])) AND
        (@bounds.Filter([Location]) = 1)
END
ELSE
BEGIN
    SELECT [ID], [Name], [Type], [Data], [MinLOD], [MaxLOD], [Location].[Lat] AS [Latitude], [Location].[Long] AS [Longitude], [SourceID]
    FROM [POIs]
    WHERE
        NOT ((@maxLOD < [MinLOD]) OR (@minLOD > [MaxLOD])) AND
        (@bounds.STIntersects([Location]) = 1)
END

END

The 'POI' table has an index on MinLOD, MaxLOD, and a spatial index on Location.