完整性要求

• 我读完了 issue 模板中的所有注释，确保填写符合要求。
• 我保证阅读了文档，了解所有我编写的配置文件项的含义，而不是大量堆砌看似有用的选项或默认值。
• 我提供了完整的配置文件和日志，而不是出于自己的判断只给出截取的部分。
• 我搜索了 issues, 没有发现已提出的类似问题。
• 问题在 Release 最新的版本上可以成功复现

描述

WireGuard outbound throughput dropped from ~200 Mbps (v25.12.8) to ~100-120 Mbps (v26.3.27) for single-peer outbound configurations.

Root cause: commits d8a8629 and 67a71ad changed the read path in proxy/wireguard/bind.go.

Old behavior (v25.12.8): The receive function sent an empty buffer via channel to the read goroutine, which read directly into it (zero-copy). One allocation, one copy.

New behavior (v26.3.27): The read goroutine allocates a new []byte of device.MaxMessageSize (~65KB) for every UDP packet, reads into it, sends via channel, then the receive function copies it again via copy(bufs[0], r.buff).

This causes:

1. Per-packet heap allocation of ~65KB (make([]byte, device.MaxMessageSize)) — heavy GC pressure at high throughput
2. Double data copy (read into temp buffer → copy into WireGuard buffer)

At 200 Mbps with ~1400 byte packets, this is ~17,000 allocations/sec of 65KB each ≈ 1.1 GB/sec of allocations.

Suggested fix: Use sync.Pool for buffer reuse instead of make() per packet, and consider reading directly into the destination buffer to eliminate the double copy.

重现方式

1. Configure a WireGuard outbound with a single peer
2. Run speed test on v25.12.8 → ~200 Mbps download
3. Run speed test on v26.3.27 with the same config → ~100-120 Mbps download
4. Server: Linux amd64, VPS in Germany

客户端配置

N/A — issue is on server side only

服务端配置

{
  "outbounds": [
    {
      "protocol": "wireguard",
      "settings": {
        "secretKey": "secretKey",
        "address": ["10.1.1.1/32"],
        "peers": [
          {
            "endpoint": "endpoint",
            "publicKey": "publicKey",
            "allowedIPs": ["0.0.0.0/0", "::/0"]
          }
        ],
        "domainStrategy": "ForceIPv4"
      },
      "tag": "tag"
    }
  ]
}

客户端日志

N/A

服务端日志

No errors in logs. The issue is a performance degradation, not a functional bug.