We have a very simple formula to calculate TABLEAU Report Rendering Time.

Report rendering time=Network time(request from URL to Report server) +Query execution time + Network time(response from SQL Server)+calculations(table COLUMN)+time taken to display the report in desired format(HTML/ pdf/ excel) 

• Table Calculations: These are inbuilt calculations in tableau which we normally use to calculate Percentage from or for YTD and other calculations like the measure across the table, below table and etc.
• Layout Containers in force spatial links between components of a dashboard. Conceptually, they allow the designer of the dashboard to format COMMON elements and simultaneously move several dashboard objects. 

One of two choices includes layout containers: horizontal or vertical. 

• The developer can group working sheets and dashboards from right through the PAGES with horizontal design containers and edit all elements at once. 
• Up to the bottom of your page, vertical containers enable the user to group workshop sheets as well as dashboards and modify the width of all elements.

• Horizontal and vertical components: We can use these to transfer all sheets or filters in one shot. However, without this, we can still GENERATE the dashboard. It enables us to simplify our job