private void Form1_Load(object sender, EventArgs e)
{
    fpSpread1.Sheets[0].RowCount = 100000;
    FarPoint.Win.Spread.CellType.CheckBoxCellType check = new FarPoint.Win.Spread.CellType.CheckBoxCellType();
    FarPoint.Win.Spread.CellType.TextCellType text = new FarPoint.Win.Spread.CellType.TextCellType();

    // 임의로 셀 타입 설정
    Random rand = new Random();
    for(int i = 0; i< fpSpread1.Sheets[0].RowCount; i++)
    {
        if (rand.NextDouble() > 0.5d)
            fpSpread1.Sheets[0].Cells[i, 0].CellType = check;
        else
            fpSpread1.Sheets[0].Cells[i, 0].CellType = text;
    }
            
    // CellDoubleClick 이벤트 추가
    fpSpread1.CellDoubleClick += FpSpread1_CellDoubleClick;
}

bool flag = false;

private void FpSpread1_CellDoubleClick(object sender, FarPoint.Win.Spread.CellClickEventArgs e)
{
    // 첫번째 컬럼의 컬럼 헤더를 더블클릭했을 때, 전체 체크/해제
    if (e.ColumnHeader && e.Column == 0)
    {
        // 시간 측정 시작
        System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
        sw.Start();

        // 레이아웃 로직을 일시정지
        fpSpread1.SuspendLayout();

        flag = !flag;
        for (int i = 0; i < fpSpread1.Sheets[0].RowCount; i++)
        {
            if(fpSpread1.Sheets[0].Cells[i, 0].CellType.ToString() == "CheckBoxCellType")
            {
                fpSpread1.Sheets[0].Cells[i, 0].Value = flag;
            }
        }
        // 레이아웃 로직 재시작
        fpSpread1.ResumeLayout();

        // 시간 측정 종료
        sw.Stop();
        MessageBox.Show("time : " + sw.ElapsedMilliseconds + "ms");
    }
}