Performance and Cost

All measurements from real integration tests in us-east-1 with t4g.nano instances and 128 MB Lambda memory.

Startup Latency

Scenario	Time to connectivity
First workload (cold create)	~10.7 s
Restart from stopped	~8.5 s
NAT already running	Instant

Cold create breakdown

 0.0 s   Workload enters "pending"
 0.3 s   EventBridge delivers event
 0.4 s   Lambda cold start (55 ms init)
 0.9 s   Reconcile: observe state, decide to create NAT
 2.3 s   RunInstances returns — NAT is "pending"
         Lambda returns.

~8.0 s   NAT reaches "running" (EC2 boot + fck-nat config)
~8.3 s   EventBridge delivers NAT "running" event
~8.9 s   Lambda: allocate EIP + associate (~3 s)

~10.7 s  Workload can reach the internet

The ~8 second gap is EC2 instance lifecycle (placement, OS boot, iptables config) — not the Lambda.

Restart breakdown

 0.0 s   New workload enters "pending"
 0.4 s   Lambda finds stopped NAT → StartInstances
         Lambda returns.

~6.0 s   NAT reaches "running" (faster than cold create)
~6.3 s   Lambda: allocate EIP + associate

~8.5 s   Workload can reach the internet

Restart is ~2 seconds faster — StartInstances skips AMI resolution and launch template processing.

Lambda Execution

Metric	Value
Cold start (Init Duration)	55 ms
Typical invocation	400-600 ms
EIP allocation + association	~3 s
Peak memory	29-30 MB
Lambda memory allocation	128 MB

The Lambda is a compiled Go ARM64 binary on provided.al2023. No interpreter, no framework — just direct AWS SDK calls.

Scale-Down Timing

 0.0 s   Last workload enters "shutting-down"
 0.3 s   EventBridge delivers event
 0.5 s   Lambda: reconcile → workloads=0, NAT running → stopNAT
         Lambda returns.

~10 s    NAT reaches "stopped"
~10.3 s  EventBridge delivers NAT "stopped" event
~10.5 s  Lambda: release EIP

~11 s    EIP released, no IPv4 charge

Cost

Per AZ, per month. us-east-1 on-demand prices. Includes the $3.60/month public IPv4 charge.

State	nat-zero	fck-nat	NAT Gateway
Idle	~$0.80	~$7-8	~$36+
Active	~$7-8	~$7-8	~$36+

Idle: EBS volume only (~$0.80 for 2 GB gp3). No instance, no EIP.

Active: t4g.nano ($3.07) + EIP ($3.60) + EBS ($0.80) = ~$7.50.

Instance types

Type	Network	$/month (24x7)	$/month (12hr/day)
t4g.nano (default)	Up to 5 Gbps	$3.07	$1.53
t4g.micro	Up to 5 Gbps	$6.13	$3.07
t4g.small	Up to 5 Gbps	$12.26	$6.13
c7gn.medium	Up to 25 Gbps	$45.55	$22.78

Spot pricing typically offers 60-70% savings. Use market_type = "spot".

t4g.nano handles typical dev/staging traffic. Instance type does not affect startup time — the bottleneck is EC2 lifecycle, not CPU.