SSAS Slowness when getting more granular data beyond pre-aggregated data

Question

I've inherited a SSAS Cube and know nothing about SSAS and trying to figure out next steps.

Symptoms are the pre-aggregated cubes and partitions are running fast. However, when drilling into the lower level granular data sets, the time to see the data in the Excel Pivot tables can take upwards of 10 minutes, although generally 1-2 minutes. This does vary pretty widely at time however.

We're running SQL SSAS 2022 Enterprise Edition.

Based upon a Microsoft Article, I setup an Extended Event trace to capture some basic data. It seems the queries are what is taking a while. A sample query is below.

SELECT 
    NON EMPTY Hierarchize({DrilldownLevel({[CostP Process Attributes].[Cost Category].[All]},,,INCLUDE_CALC_MEMBERS)}) 
        DIMENSION PROPERTIES PARENT_UNIQUE_NAME
            ,HIERARCHY_UNIQUE_NAME ON COLUMNS 
            , NON EMPTY CrossJoin(Hierarchize({DrilldownLevel({[CostP Product Attributes].[Stars Fund Id Like S].[All]},,,INCLUDE_CALC_MEMBERS)})
            , Hierarchize({DrilldownLevel({[CostP Product Attributes].[Stars Fund Name Like S].[All]},,,INCLUDE_CALC_MEMBERS)})) 
        DIMENSION PROPERTIES PARENT_UNIQUE_NAME,HIERARCHY_UNIQUE_NAME ON ROWS  
            FROM (SELECT ({[Time].[Month].&[2024-01-01T00:00:00]
                ,[Time].[Month].&[2024-02-01T00:00:00]
                ,[Time].[Month].&[2024-03-01T00:00:00]
                ,[Time].[Month].&[2024-04-01T00:00:00]
                ,[Time].[Month].&[2024-05-01T00:00:00]
                ,[Time].[Month].&[2024-06-01T00:00:00]
                ,[Time].[Month].&[2024-07-01T00:00:00]
                ,[Time].[Month].&[2024-08-01T00:00:00]
                ,[Time].[Month].&[2024-09-01T00:00:00]
                ,[Time].[Month].&[2024-10-01T00:00:00]
                ,[Time].[Month].&[2024-11-01T00:00:00]}) 
            ON COLUMNS  FROM [CostP Partition]) 
            WHERE ([Time].[Year].&[2024-01-01T00:00:00]
                ,[CostP Client Attributes].[Client Name].[All]
                ,[CostP Channel Attributes].[MKTG Chn One].[All]
                ,[CR Cost Center Hierarchy Detail].[Schedule 5   Department Group].[All]
                ,[CR Cost Center Hierarchy Detail].[Department Number CC].[All]
                ,[CR Cost Center Hierarchy Detail].[Performance Group].[All]
                ,[CostP Process Attributes].[Process].[All]
                ,[Measures].[Costs]
            ) CELL PROPERTIES VALUE, FORMAT_STRING, LANGUAGE, BACK_COLOR, FORE_COLOR, FONT_FLAGS

I'm guessing these aren't pre-written, but being auto generated by Excel based upon how the end user is slicing and dicing the data in the pivot table. This is only a guess, as I'm not even sure if the code is MDX, DMX, or something else entirely.

Where do I go from here? How do I start to optimize the code? Are there indexes that I can add for such things? Is there something else I should be looking at.

Appreciate any help, direction, support, etc.