Supabase Realtime latency spikes under concurrent WebSocket connections

Goal: Determine whether the increase in broadcast latency observed in Supabase Realtime is caused by connection‑pool exhaustion, PgBouncer backpressure, or Node.js event‑loop lag when many clients open WebSocket connections simultaneously.

Constraints: The threshold at which latency becomes noticeable is unknown and may differ between free and paid project tiers; network jitter could also contribute. Uncertainty remains about which internal metric best predicts the latency rise and whether the behavior is intrinsic to the managed service or specific to a project’s configuration.

Questions: What concurrent WebSocket connection count begins to produce measurable latency increase? Which metric—PgBouncer wait time, Node.js loop lag, or database replication lag—correlates most strongly with the observed latency? Do latency patterns diverge between free and paid Supabase projects under identical load conditions?