Hi @HoaiNamNguyen ，
There are 3 places where the refresh might be slow:
1.Data source
2.Power Query engine
3.Analysis Services engine
Test the below steps:
1. Please check whether there existing any step in Power Query consuming too much CPU or memory. And try to use Table.Buffer to improve the data load performance.
2. Use DAX studio/ Performance Analyzer to check out which's the most time-consuming:
Follow this blog to install the dax studio,then connect the opened pbix file in dax studio
https://docs.microsoft.com/en-us/power-bi/desktop-performance-analyzer
3. If your data source is online such as in onedrive or sharepoint online, they use automatic refresh in power bi service. This means no user configuration is necessary in order for the dataset to be refreshed on a regular basis. Data refresh settings are configured for you by Power BI. For online service providers, refresh usually occurs once-a-day. For files loaded from OneDrive, automatic refresh occurs about every hour for data that does not come from an external data source. While you can configure different schedule refresh settings and manually refresh, you probably don’t need to.
And refer:
https://medium.datadriveninvestor.com/my-dataset-is-taking-too-long-to-refresh-843fd8fd4a51
Best Regards
Lucien
