Understanding bad performances for a Power BI solution

Hi,

I've implemented a PBI solution by importing data from two sources in order to produce a report.

The model has many fact tables and dimensions with only unidirectional relationships.

The report has a table visual that exposes about 25 measures, 3 page filters and 2 slicers.

When the report is selected it takes 3 minutes to show the data in the visual.

After a model review, I've excluded some unused tables and the execution time is becomed to 30 seconds.

For me, it is a strange behaviour to understand: how unused tables could affect the performance of a PBI report?

I've used DAX studio to analyze this behaviour: it seems that I need to do something about DAX optimitazions,

but the measures all the same before and after the unused tables deletion from the table.

Now, I'd like understanding this strange behaviour: unused tables in a report could affect the querying time?

Thanks