C#

class Grid : System.Windows.Forms.DataGridView {

        internal void SetDataRetriever(DataRetriever<TEntity> dataRetriever)
        { ......
            SuspendLayout();
            Enabled  = false;
            int cnt = DataRetriever.RowCount + (ReadOnly ? 0 : 1);
            // next line takes 8 seconds:
            RowCount = cnt;
            Enabled = true;
            ResumeLayout();
        }

        protected override void
OnCellValueNeeded(DataGridViewCellValueEventArgs e)
        {
            if (!Enabled)
                return;
             ...
        }

        protected override void OnRowEnter(DataGridViewCellEventArgs e)
        {
            if (!Enabled)
                return;
            ...
         }
}