For optimal performance, it is recommended to limit the data to what is necessary for analysis, which in this case would be the current and previous years. Moving the calculation of averages to the data layer and aggregating the dates to a monthly level will reduce the granularity of the data, thereby improving the performance of the dashboard.This approach aligns with best practices foroptimizing workbook performance in Tableau, which suggest simplifying the data model and reducing the number of records processed12.

References:The recommendation is based on the guidelines provided in Tableau’s official documentation on optimizing workbook performance, which includes tips on data management and aggregation for better performance12.