Hi,

How do you get the interval? By default, there are 60 frames per second in silverlight, which means it's 15-16 millseconds between frames.

If we calculate interval in CompositionTarget.Rendering event, then we would get 15-16 millseconds timespan.

To be more accurate, we could use TimeSpan.Ticks property, check this sample

        public MainPage()
        {
            InitializeComponent();
            CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);
        }

        int precount; DateTime pretime;
        void CompositionTarget_Rendering(object sender, EventArgs e)
        {
            string str = "datetime.now.ticks:";
            DateTime time = DateTime.Now;
            str += (time-pretime).Ticks;
            pretime = time; 

            str += "environment.tickscount";
            int count = Environment.TickCount;
            str += count-precount;
            precount = count;

            textblock1.Text = str; 
        }