In this lesson, you will learn how to prevent network congestion by implementing custom frequency throttling for your Remote Procedure Calls (RPCs).
While Unreal Engine automatically handles the bandwidth for replicated properties, RPCs are "fire-and-forget" events that can easily overwhelm the network buffer if triggered too frequently—such as in a high-intensity "Rapid Fire" ability or a constant status update loop. If you trigger an unreliable Multicast RPC every single frame, you risk packet loss and jitter for all connected clients.
Implementing a Throttling Guard
The most efficient way to throttle RPC frequency is to implement a local timer or a "last execution" timestamp check before calling the RPC. By comparing the current game time against a defined threshold, you can drop redundant calls before they ever hit the network pipe.
Consider this example of a player firing a weapon or sending a data-heavy update:
void AMyCharacter::Server_SendUpdate_Implementation(FVector Data)
{
// Logic to update the server state
}
void AMyCharacter::TrySendUpdate(FVector Data)
{
float CurrentTime = GetWorld()->GetTimeSeconds();
// Only allow the RPC to fire if 0.1 seconds (10Hz) have passed
if (CurrentTime - LastRPCTime > 0.1f)
{
Server_SendUpdate(Data);
LastRPCTime = CurrentTime;
}
}
Why Throttling Matters
By implementing this gate, you convert an unpredictable "frame-rate-dependent" burst of traffic into a steady, predictable stream. This is critical for gameplay sequences like cosmetic status effects, UI updates, or non-essential environmental interactions.
If your game logic requires a high-frequency update, always evaluate if the data needs to be an RPC. If the server only needs the final state, consider using a Replicated variable instead, as Unreal’s internal NetUpdateFrequency system is already optimized to batch and throttle property changes far better than raw RPCs. Use RPC frequency throttling strictly for transient, non-critical event triggers that occur faster than the network can reliably sustain.
Key Takeaway: Use local timestamp checks to gate your RPC triggers, ensuring that your network traffic remains within a sustainable bandwidth budget during high-intensity gameplay.