Hi Sabareesh,
Thank you for your interest in Syncfusion Products.
Instead of assigning the CellValue / Text for the cells, you can directly load into GridData which will make the population very very faster. Please find the simple sample in the following link that illustrates this:
http://websamples.syncfusion.com/samples/Grid.Windows/F71275/main.htmPlease let me know if any concerns.
Regards,
Fathima