CollectiveTimer reduces timer allocations.

03-TimerContention-03.cs

public class CollectiveTimer<T>
{
    private readonly ConcurrentQueue<QueueItem> _queue;
    public CollectiveTimer(Action<T> action, TimeSpan timeout, CancellationToken cancellationToken)
    {
        _queue = new ConcurrentQueue<QueueItem>();
        Task.Run(async () =>
        {
            while (!cancellationToken.IsCancellationRequested)
            {
                QueueItem queueItem;
                var now = DateTime.UtcNow;
                while (_queue.TryPeek(out queueItem) && now - queueItem.Time >= timeout)
                {
                    _queue.TryDequeue(out queueItem);
                    action(queueItem.Item);
                }

                await Task.Delay(TimeSpan.FromMilliseconds(50));
            }
        });
    }
    public void Enqueue(T item)
    {
        _queue.Enqueue(new QueueItem(item, DateTime.UtcNow));
    }
    private sealed class QueueItem
    {
        public T Item { get; private set; }
        public DateTime Time { get; private set; }
        public QueueItem(T item, DateTime time)
        {
            Item = item;
            Time = time;
        }
    }
}