If the range deleter encounters a task to delete a range of a collection with a hashed shard key but without a hashed shard key index, it will eventually skip it and reinsert it at the end of the queue. If that is the only task remaining in the queue, the main loop of the range deleter effectively degenerates to a tight loop where it is skipping and reinserting tasks to the queue as fast as the CPU allows, hogging the CPU unnecessarily.