Skip to main content
Showing results for 
Search instead for 
Did you mean: 

The ultimate Microsoft Fabric, Power BI, Azure AI & SQL learning event! Join us in Las Vegas from March 26-28, 2024. Use code MSCUST for a $100 discount. Register Now

Frequent Visitor

Poor performance in data refresh using multiple large CSV files

Power BI newbie here. I have large CSV files scattered on multiple directories. I specify datasource using Get Data > More > Folder. , Its taking too long when you hit refresh to get updated data. Does Power BI re-read all CSV files even if they are not updated? Is it better to have 1 large csv files compared to just incrementally adding new csv for every update?


Super User
Super User

Hi @jerald,


Having worked quite a lot with CSV's it would be ideal to put all the data into on CSV file, so it does not have to and read all the individual files.


Also currently there is no incremental refresh option as you have indicated.


You can refer to my blog post below, where I give some tips in terms of how to process CSV files as quickly as possible.


Power BI – Quick Tips working with multiple large CSV Files

Did I answer your question? Mark my post as a solution!

Proud to be a Super User!

Power BI Blog

Community Support
Community Support

Hi @jerald,


You can turn off refresh function in query editor:


1. Open query editor.
2. Choose the query which you don't want to refresh.
3. Right-Click on it and turn off the "Include In Report Refresh" option.



Xiaoxin Sheng

Community Support Team _ Xiaoxin
If this post helps, please consider accept as solution to help other members find it more quickly.

Hi @v-shex-msft,


I forgot to mention that this multiple csv files are in only 1 query. I was hoping that Power BI supports incremental refresh but I recently found out that this is not supported.



Helpful resources

Fabric Community Conference

Microsoft Fabric Community Conference

Join us at our first-ever Microsoft Fabric Community Conference, March 26-28, 2024 in Las Vegas with 100+ sessions by community experts and Microsoft engineering.

February 2024 Update Carousel

Power BI Monthly Update - February 2024

Check out the February 2024 Power BI update to learn about new features.

Fabric Career Hub

Microsoft Fabric Career Hub

Explore career paths and learn resources in Fabric.

Fabric Partner Community

Microsoft Fabric Partner Community

Engage with the Fabric engineering team, hear of product updates, business opportunities, and resources in the Fabric Partner Community.