Fastest way to edit cell - direct access to the Node.Value:
[c#]
public void SetValue(FlyGrid flyGrid, NodeBase node, object value)
{
int index = flyGrid.Columns.FieldMapIndexOf(\"someField\");
object[] value = node.Value as object[];
value[index] = value;
}
Also you can see another method in the FlyGrid Demo (performanceForm.cs, refreshDataBtn_Click method).
Do not use grid.Begin/EndUpdate(), use BeginInit/EndInit pair when you make block of cell updates.