public partial class Page1 { public Page1() { this.InitializeComponent(); this.Entry.TextChanged += this.EntryOnTextChanged; } 

                            private CancellationTokenSource throttleCts = new CancellationTokenSource();

                            private void EntryOnTextChanged(object sender, TextChangedEventArgs args) { 

                                Interlocked.Exchange(ref this.throttleCts, new CancellationTokenSource()).Cancel(); Task.Delay(TimeSpan.FromMilliseconds(500), this.throttleCts.Token) // throttle time

                                    .ContinueWith( delegate { this.HandleString(this.Entry.Text); }, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.FromCurrentSynchronizationContext()); }

                            private void HandleString(string str) { /*..*/ }