Following my last tutorial, I have updated the COVID-19 Power BI app on AppSource (download it here) and added incremental confirmed cases and deaths columns using Power Query. While the refresh is now longer, you can see in the screenshot below that the calculation time is significantly improved (around 2-10 times faster). For one of the slowest visuals, it took 12 seconds to load before the optimization and now is a bit above two seconds.
Check out the embedded version below and see how fast it loads now. The most challenging report page was the US page since the fact table includes all permutations of states, counties, and dates since COVID-19 started last year.
You can get the complete source code and PBIX file on DataChant shop here.
Nice work! Where exactly are you getting the data from?
I use JHU CSSE COVID-19 Data:
https://github.com/CSSEGISandData/COVID-19
You can follow my early COVID-19 tutorials to learn how I did it step by step.