I am not an expert, but in terms of crowd I estimate it can be crowded in certain areas, but I do not think that necessarily translates as long wait times for attractions. This event is a little spread out as there is multiple activities and more than one stage so there will be crowds, but since this is a ticketed event I would imagine most of these individuals are focusing on enjoying the events / concerts, not the attractions, or at least not that much. I do not go to HHN religiously (no pun intended), but the times I've gone even then the attraction lines were not that long, especially compared to the houses. It could be different depending on the night I would imagine (as I never went during peak HHN days). Necessarily won't mean others won't enjoy those attractions, but I can imagine the attractions will get less attention since this is a ticketed event aimed for a specific audience and promising something not typically offered at Universal. If anything, wait times should be definitely low during times in which concerts are held, or other events.