Comment by yashasolutions

One obvious downside is that polling at a fixed interval is going to be less efficient than having an event "pushed" to your client as soon as it's available. If your events are low-volume, then there will be periods where your polling requests return no new data, but you still have to make those requests anyway in order to determine that. And conversely, if your events are high-volume, then your polling interval represents an arbitrary amount of delay that you're introducing into the system. That might not be big deal for some applications, but it's worth mentioning as a potential downside in situations where you want the behavior to be as near-instantaneous as possible.