Go vs .NET NATS Server — Benchmark Comparison
Benchmark run: 2026-03-13. Both servers running on the same machine, tested with identical NATS.Client.Core workloads. Test parallelization disabled to avoid resource contention.
Environment: Apple M4, .NET 10, Go nats-server (latest from golang/nats-server/).
Core NATS — Pub/Sub Throughput
Single Publisher (no subscribers)
| Payload |
Go msg/s |
Go MB/s |
.NET msg/s |
.NET MB/s |
Ratio (.NET/Go) |
| 16 B |
2,436,416 |
37.2 |
1,425,767 |
21.8 |
0.59x |
| 128 B |
2,143,434 |
261.6 |
1,654,692 |
202.0 |
0.77x |
Publisher + Subscriber (1:1)
| Payload |
Go msg/s |
Go MB/s |
.NET msg/s |
.NET MB/s |
Ratio (.NET/Go) |
| 16 B |
1,140,225 |
17.4 |
207,654 |
3.2 |
0.18x |
| 16 KB |
41,762 |
652.5 |
34,429 |
538.0 |
0.82x |
Fan-Out (1 Publisher : 4 Subscribers)
| Payload |
Go msg/s |
Go MB/s |
.NET msg/s |
.NET MB/s |
Ratio (.NET/Go) |
| 128 B |
3,192,313 |
389.7 |
581,284 |
71.0 |
0.18x |
Multi-Publisher / Multi-Subscriber (4P x 4S)
| Payload |
Go msg/s |
Go MB/s |
.NET msg/s |
.NET MB/s |
Ratio (.NET/Go) |
| 128 B |
269,445 |
32.9 |
529,808 |
64.7 |
1.97x |
Core NATS — Request/Reply Latency
Single Client, Single Service
| Payload |
Go msg/s |
.NET msg/s |
Ratio |
Go P50 (us) |
.NET P50 (us) |
Go P99 (us) |
.NET P99 (us) |
| 128 B |
9,347 |
7,215 |
0.77x |
104.5 |
134.7 |
146.2 |
190.5 |
10 Clients, 2 Services (Queue Group)
| Payload |
Go msg/s |
.NET msg/s |
Ratio |
Go P50 (us) |
.NET P50 (us) |
Go P99 (us) |
.NET P99 (us) |
| 16 B |
30,893 |
25,861 |
0.84x |
315.0 |
370.2 |
451.1 |
595.0 |
JetStream — Publication
| Mode |
Payload |
Storage |
Go msg/s |
.NET msg/s |
Ratio (.NET/Go) |
| Synchronous |
16 B |
Memory |
16,783 |
13,815 |
0.82x |
| Async (batch) |
128 B |
File |
187,067 |
115 |
0.00x |
Note: Async file store publish is extremely slow on the .NET server — likely a JetStream file store implementation bottleneck rather than a client issue.
JetStream — Consumption
| Mode |
Go msg/s |
.NET msg/s |
Ratio (.NET/Go) |
| Ordered ephemeral consumer |
109,519 |
N/A |
N/A |
| Durable consumer fetch |
639,247 |
80,792 |
0.13x |
Note: Ordered ephemeral consumer is not yet fully supported on the .NET server (API timeout during consumer creation).
Summary
| Category |
Ratio Range |
Assessment |
| Pub-only throughput |
0.59x–0.77x |
Good — within 2x |
| Pub/sub (large payload) |
0.82x |
Good |
| Pub/sub (small payload) |
0.18x |
Needs optimization |
| Fan-out |
0.18x |
Needs optimization |
| Multi pub/sub |
1.97x |
.NET faster (likely measurement artifact at low counts) |
| Request/reply latency |
0.77x–0.84x |
Good |
| JetStream sync publish |
0.82x |
Good |
| JetStream async file publish |
~0x |
Broken — file store bottleneck |
| JetStream durable fetch |
0.13x |
Needs optimization |
Key Observations
- Pub-only and request/reply are within striking distance (0.6x–0.85x), suggesting the core message path is reasonably well ported.
- Small-payload pub/sub and fan-out are 5x slower (0.18x ratio). The bottleneck is likely in the subscription dispatch / message delivery hot path — the
SubList.Match() → MSG write loop.
- JetStream file store is essentially non-functional for async batch publishing. The sync memory store path works at 0.82x parity, so the issue is specific to file I/O or ack handling.
- JetStream consumption (durable fetch) is 8x slower than Go. Ordered consumers don't work yet.
- The multi-pub/sub result showing .NET faster is likely a measurement artifact from the small message count (2,000 per publisher) — not representative at scale.
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