Jitter

Jitter describes how much latency varies from packet to packet. If every packet took exactly 30 ms there would be zero jitter; if delays bounce between 20 ms and 90 ms, jitter is high. It is caused by congestion, changing network paths and queuing inside routers. For steady bulk transfers jitter barely matters, but for real-time streams — voice, video, gaming — it is often more disruptive than a slightly higher but stable delay, because buffers cannot smooth out unpredictable arrivals.

Adding a hop such as a proxy or VPN can change your jitter for better or worse: a congested intermediate path raises it, while a well-provisioned one can be steadier than your default route. Real-time applications combat jitter with a jitter buffer that briefly holds packets so they can be played back at an even pace, trading a little latency for smoothness. If a real-time task feels choppy through a connection, sample the round trip repeatedly rather than once — a good average can still hide damaging variance that only a series of measurements reveals.

Routing, congestion and the target affect latency and throughput. Compare the same workload through each relevant path at several times instead of assuming predictable performance from a region. s4m supports WireGuard and OpenVPN profiles. The issued profile and client routing determine the exit and which traffic follows the tunnel. Related topics: VPN, proxy.