I was recently getting an error when refreshing an Excel file that was stored in SharePoint online.
This got me thinking what the issue is and is there a way to improve it and YES there is as detailed below.
When I investigated this further, I found that my 17kb Excel file was using at least 616kb of data when being refreshed in Power BI Desktop. Whilst this is a relatively small amount this is 36x larger than the file size. This led me to believe that it is possibly being read multiple times, but some other things might be going on!
Spoilers: there were things going on.