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Power BI: Comparing Web.Contents and File.Contents Performance

Chris Webb compares the performance of File.Contents and Web.Contents:

In my last post I mentioned the Power Query engine’s persistent cache, which in some scenarios caches the data read from a data source when a query is refreshed. Another important nugget of information that Ehren von Lehe of the Power Query dev team mentioned in a post on the Power Query MSDN forum recently is the fact that if you use File.Contents to get data from a file then the persistent cache is not used, but if you use Web.Contents to get data from the same file then the persistent cache is used. I guess the thinking here is that there is no point creating an on-disk cache containing the contents of a file that is already on disk.

Chris takes us through a couple of unexpected twists, so check it out.