SignalR vs Polling: Choosing the Right Real-Time Strategy
A practical comparison of long-polling and SignalR for live updates, with guidance on when each wins.
"Real-time" spans a huge range of needs. Before reaching for WebSockets, it's worth asking how fresh your data actually needs to be.
Polling
Polling is dead simple: the client asks for updates on an interval. It's stateless, cache-friendly, and works everywhere.
setInterval(async () => {
const res = await fetch("/api/sections/availability");
setSeats(await res.json());
}, 5000);The cost is latency and wasted requests when nothing changed.
SignalR
SignalR maintains a persistent connection and pushes updates the instant they happen. It handles transport negotiation (WebSockets, SSE, long-polling) for you.
await hubContext.Clients
.Group(sectionId)
.SendAsync("SeatsChanged", seatsLeft);SignalR shines when updates are frequent and low-latency matters — dashboards, chat, collaborative editing, live seat counts.
How to choose
| Need | Prefer |
|---|---|
| Updates every few minutes | Polling |
| Sub-second latency | SignalR |
| Massive fan-out, simple infra | Polling + cache |
| Bidirectional messaging | SignalR |
Takeaway
Use polling until latency or request volume hurts — then reach for SignalR. Matching the tool to the freshness requirement keeps your infrastructure simple.