讨论关于 jfreechart的曲线图时间长会让窗口卡的问题

这是我的代码：
这是一个监控程序
ti = new Timer(1000, new ActionListener() {
          public void actionPerformed(ActionEvent e) {
          ArrayList<SensorSimData> list = new ArrayList<SensorSimData>();
for (SensorSimData ss: out.huangcun) {
if (ss.sbbh == sbbh && ss.addr == addr) {
list.add(ss);
}
}
qxt.refreshMap(list);
tqxt.refreshMap(list);
rqxt.refreshMap(list);
lqxt.refreshMap(list);
sxqxt.refreshMap(list);
syqxt.refreshMap(list);
szqxt.refreshMap(list);
list=null;
}
});
qxt = new QuXianTu_dongtai(out, sbbh, addr);
tqxt = new Temp_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
rqxt = new Rssi_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
lqxt = new Light_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
sxqxt = new SpeedX_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
syqxt = new SpeedY_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
szqxt = new SpeedZ_QuXianTu_dongtai(out, sbbh, addr, gaodixian);
jInternalFrame1.setContentPane(qxt.createDemoPanel());
jInternalFrame2.setContentPane(tqxt.createDemoPanel());
jInternalFrame3.setContentPane(rqxt.createDemoPanel());
jInternalFrame4.setContentPane(lqxt.createDemoPanel());
jInternalFrame5.setContentPane(sxqxt.createDemoPanel());
jInternalFrame6.setContentPane(syqxt.createDemoPanel());
jInternalFrame7.setContentPane(szqxt.createDemoPanel());

这是swing的对话框，在这个对话框中有7个JInternalFrame每一个都画曲线图，通过timer的在动态的画曲线图


这是我其中一个JInternalFrame中曲线图代码：
public JPanel createDemoPanel() {

JFreeChart chart = createChart();
return new ChartPanel(chart);
}
void refreshMap(ArrayList<SensorSimData> list){
for (Iterator<SensorSimData> it = list.iterator(); it.hasNext();) {
SensorSimData hd = it.next();
if (hd.sbbh == sbbh && hd.addr == addr) {
gaoxian.addOrUpdate(new Millisecond(), gaodixian.get(0));
dixian.addOrUpdate(new Millisecond(), gaodixian.get(1));
timeSeries1.addOrUpdate(new Millisecond(hd.date), Double
.parseDouble(hd.temp));
}
}
}


开始的时候还行，很稳定，对话框一点都不卡，可是过了一个小时再看时，程序稳定没出错，但是对话框拖动反应非常慢很卡，不知到各位大侠有没有碰到类似的问题？