施用tick函数，产生操作延时

使用tick函数，产生操作延时
我用按钮控制timer的enable属性，但是总是会产生操作延时，是什么原理啊？求参考资料。
下附代码：

C# code

 private void timer1_Tick(object sender, EventArgs e)        {            this.progressBar1.Value = (timercounter);//updata the progress bar            //updata the label of time show            int result = this.TimeCalculate(out TimeShow);            this.lb_TimeShow.Text = TimeShow;                                        //alarm of time up            if (timercounter == frm_Start.TimeLimit)            {                this.progressBar1.Value = (frm_Start.TimeLimit);                this.timer1.Enabled = false;            }            timercounter++;        }        private void btn_OnHold_Click(object sender, EventArgs e)        {            timer1.Enabled = false;            btn_StartTimer.Enabled = true ;        }