Power Query - Very Slow - Loading lots of Data

[Anonymous]

Hello,

when doing ETL in PBI Desktop my Power Query is loading lots of data. Whenever I do a new step in the applied steps area, the litle lable in the bottom right corner shows a very high number of data being loaded, like 100mb. This takes very long. Sometimes it says not the amount of data bot the rows loaded. In that case its like 500000 rows loaeded. Why does this happen?

My preview feature is set to 1000 rows. I would expect that no more should be loaded.

This makes development very slow.

I would appreciate any help!

Greetings

Mike

[amitchandak]

@Anonymous , the step will be applied to all data.  Just check power BI taking enough RAM and CPU

[Greg_Deckler]

@Anonymous - I have witnessed this behavior on Power BI files with lots of queries and relatively complex queries. I am not sure of the cause other than perhaps how the query is structured it has to load all of the rows in order to generate the preview. But, I agree it is highly annoying when it happens but I am not sure I have ever found a root cause for it.