Hi Bryan,
Thanks for your interest in Syncfusion Products.
We have analysed your Query. As you have mentioned that there occurs some performance issue when you hide a range of rows, you can make use of "UseOldHiddenScrollLogic" and set it to true or you can use :
this.gridGroupingControl1.TableControl.EnableDoubleBufferSurface()
This will resolve your issue.
Regards,
Athiram S