Calculation group performance issue

Hello everyone,

I face an issue about performance when I use calculation groups in my model. To give some context items, my dataset is quite complex (around 40 tables) and is stored on a premium capacity P2. It's a composite model that is using the user defined agregation feature of Power BI so we manage a detailed fact table and an aggregated one.

To simplify my case, please consider the example below :

- I have one measure "Amount" (sum of my fact table)

- I have one measure "Amount Last Year"

- I have a calculation group with one item that calculate Last Year value for the selected KPI 

- Then, I create two matrix on my report : 
      - One is using the measure "Amount Last Year" to display last year amount per fiscal period

      - One is using the measure "Amount" on which I apply the calculation item "Last Year" to display last year amount per fiscal period 

When I compare the performance of the two visuals, I face a very big gap in term of performance.

This example is a lot more simplified than the visual i'm creating for my reporting purpose. In real situation, visuals are taking to much time when I use calculation groups so it's not possible to use them.

Does someone have any idea about where this performance gap could come from ?

Thanks,

R_LB