Use dispatcher timer for every Function
public class ViewModel{
private static System.Timers.Timer aTimer;
public ViewModel()
{
aTimer = new Timer();
aTimer.Interval = 2000;
aTimer.Elapsed += DoWork;
aTimer.AutoReset = true;
aTimer.Enabled = true;
}
public void DoWork(Object source, System.Timers.ElapsedEventArgs e) {
}
}