Thank you for contacting Syncfusion support.
Query regarding improve the rendering performance for new data’s:
We have analyzed your query and when we have many numbers of column’s with ColumnSizer.Star, it will take some time for loading because Star ColumnSize will divided column’s width is equally based on the total space. You can use ColumnSizer as None or Auto instead of using Star ColumnSizer, it will improve the performance when you use many number of column’s. If you didn’t use validation, you can customizing GridCell style for improve the loading performance in SfDataGrid. We have attached the sample with customized GridCell style, please refer it.
Sample link: http://www.syncfusion.com/downloads/support/forum/118962/SfDataGridDemo_DT-1306159584.zip
Please let us know if you require further assistance.