How to improve performance of SSRS report using Cubes as data source?

Question

I am trying to build an SSRS report with SSAS as the data source. It has 4 cascading parameters. I used the SSRS Query designer to generate MDX because I am not very familiar with Cubes/MDX.

It works but takes too long to render the report (3 minutes or more in both Visual Studio and on the Reporting Server). I also tried to generate MDX using Excel OLAP Pivot table extensions and modified the MDX to use cascading parameters, but the performance isn't getting any better.

If I use SQL queries and SQL server as the data source for the same report, I get the output in a few seconds. But implementing this using cubes should make this scale much better.

Does anyone know what steps I can take to improve the performance of this report?

This is the MDX from SSRS query designer -

 SELECT NON EMPTY { [Measures].[FactCount], [Measures].[Rate], [Measures].[Benchmark1], [Measures].[Benchmark2] } ON COLUMNS, 
        NON EMPTY {{[DimOrg].[DivisionName].[All]} 
                    * {[DimMeasure].[MeasureName].[All]} 
                    * {[DimOrg].[FacilityName].[All]} 
                    * {[DimLoadDate].[RunDate].[All]} 
                    * [DimOrg].[DepartmentName].[DepartmentName].ALLMEMBERS, 
                {[DimOrg].[DivisionName].[All]} 
                    * {[DimMeasure].[MeasureName].[All]} 
                    * {[DimOrg].[FacilityName].[All]} 
                    * {[DimLoadDate].[RunDate].[All]} 
                    * {[DimOrg].[DepartmentName].[All]}, 
                ([DimOrg].[DivisionName].[DivisionName].ALLMEMBERS 
                    * [DimMeasure].[MeasureName].[MeasureName].ALLMEMBERS 
                    * [DimOrg].[FacilityName].[FacilityName].ALLMEMBERS 
                    * [DimLoadDate].[RunDate].[RunDate].ALLMEMBERS 
                    * [DimOrg].[DepartmentName].[DepartmentName].ALLMEMBERS ) } DIMENSION PROPERTIES MEMBER_CAPTION, MEMBER_VALUE, MEMBER_UNIQUE_NAME ON ROWS 
FROM (  SELECT ( STRTOSET(@DimOrgFacilityName, CONSTRAINED) ) ON COLUMNS 
        FROM (  SELECT ( STRTOSET(@DimEmployeeCategory, CONSTRAINED) ) ON COLUMNS 
                FROM (  SELECT ( STRTOSET(@DimOrgDivisionName, CONSTRAINED) ) ON COLUMNS 
                        FROM (  SELECT ( STRTOSET(@DimLoadDateLoadDate, CONSTRAINED) ) ON COLUMNS 
                                FROM (  SELECT ( { [DimLoadDate].[SomeFlag].&[True] } ) ON COLUMNS 
                                        FROM (  SELECT ( { [DimLoadDate].[someColumn].&[SomeValue] } ) ON COLUMNS 
                                                FROM (  SELECT ( { [DimMeasure].[MeasureName].&[someValue1], [DimMeasure].[MeasureName].&[someValue2] } ) ON COLUMNS 
                                                        FROM [DW]))))))) 
WHERE ( [DimLoadDate].[someColumn].&[somevalue], [DimLoadDate].[someFlag].&[True], 
        IIF( STRTOSET(@DimLoadDateLoadDate, CONSTRAINED).Count = 1, STRTOSET(@DimLoadDateLoadDate, CONSTRAINED), [DimLoadDate].[LoadDate].currentmember ), 
        IIF( STRTOSET(@DimEmployeeCategory, CONSTRAINED).Count = 1, STRTOSET(@DimEmployeeCategory, CONSTRAINED), [DimEmployee].[Category].currentmember ) ) 
CELL PROPERTIES VALUE, BACK_COLOR, FORE_COLOR, FORMATTED_VALUE, FORMAT_STRING, FONT_NAME, FONT_SIZE, FONT_FLAGS

I built another SSRS report using cubes with the same tables with a higher granularity - used 3 parameters instead of 4 and that worked faster (only a few seconds) for the report generation. Here is the MDX of that -

SELECT NON EMPTY {  [Measures].[FactCount], [Measures].[Rate], [Measures].[Benchmark1], [Measures].[Benchmark2] } ON COLUMNS, 
        NON EMPTY {{[DimOrg].[DivisionName].[All]} 
                     * {[DimMeasure].[MeasureName].[All]} 
                     * [DimOrg].[FacilityName].[FacilityName].ALLMEMBERS 
                     * {[DimLoadDate].[RunDate].[All]}, 
                {[DimOrg].[DivisionName].[All]} 
                     * {[DimMeasure].[MeasureName].[All]} 
                     * {[DimOrg].[FacilityName].[All]} 
                     * {[DimLoadDate].[RunDate].[All]}, 
                ([DimOrg].[DivisionName].[DivisionName].ALLMEMBERS 
                     *[DimMeasure].[MeasureName].[MeasureName].ALLMEMBERS 
                     * [DimOrg].[FacilityName].[FacilityName].ALLMEMBERS 
                     * [DimLoadDate].[RunDate].[RunDate].ALLMEMBERS ) } DIMENSION PROPERTIES MEMBER_CAPTION, MEMBER_VALUE, MEMBER_UNIQUE_NAME ON ROWS 
FROM ( SELECT ( -{ [DimOrg].[FacilityName].&[someValue] } ) ON COLUMNS 
         FROM ( SELECT ( STRTOSET(@DimEmployeeCategory, CONSTRAINED) ) ON COLUMNS 
                FROM ( SELECT ( STRTOSET(@DimOrgDivisionName, CONSTRAINED) ) ON COLUMNS 
                        FROM ( SELECT ( STRTOSET(@DimLoadDateLoadDate, CONSTRAINED) ) ON COLUMNS 
                                FROM ( SELECT ( { [DimLoadDate].[SomeFlag].&[True]  } ) ON COLUMNS 
                                        FROM ( SELECT ( { [DimLoadDate].[someColumn].&[SomeValue] } ) ON COLUMNS 
                                                FROM ( SELECT ( { [DimMeasure].[MeasureName].&[someValue1], [DimMeasure].[MeasureName].&[someValue2] } ) ON COLUMNS 
                                                        FROM [DW]))))))) 
WHERE ( [DimLoadDate].[someColumn].&[somevalue], [DimLoadDate].[someFlag].&[True], 
         IIF( STRTOSET(@DimLoadDateLoadDate, CONSTRAINED).Count = 1, STRTOSET(@DimLoadDateLoadDate, CONSTRAINED),  [DimLoadDate].[LoadDate].currentmember ), 
         IIF( STRTOSET(@DimEmployeeCategory, CONSTRAINED).Count = 1, STRTOSET(@DimEmployeeCategory, CONSTRAINED), [DimEmployee].[Category].currentmember ) ) 
CELL PROPERTIES VALUE, BACK_COLOR, FORE_COLOR, FORMATTED_VALUE, FORMAT_STRING, FONT_NAME, FONT_SIZE, FONT_FLAGS

Thanks,

Gopika