# Response Speed

Does a complex task take tens of minutes? The bottleneck is almost always **model generation time × Agent rounds**, not the relay layer.

## Where the Time Goes

Claude Code / Codex CLI processing a task = dozens to hundreds of API rounds. Measurements across all production requests over 24 hours:

- Model generation accounts for **93%** of total time
- Relay forwarding overhead is <1 second/request (7%)

A 30-minute task ≈ 100+ rounds × around 10 seconds per round. To make it faster, either reduce the number of rounds or switch to a faster model.

## Model Speed Reference

Measured single-request p50:

| Model | p50 | Best for |
|---|---|---|
| `gpt-5.4-mini` | ~4s | Light tasks, small changes, batch processing |
| `gpt-5.4` | ~9s | Day-to-day development |
| `gpt-5.5` | ~11s | Complex reasoning, large refactors |

The fastest and slowest differ by nearly 3×. The same applies on the Claude side: `claude-haiku-*` is faster than sonnet / opus.

## Speed-Up Recommendations

### Choose Models by Task

Do not use the heaviest model for simple tasks. For summaries, translation, and minor fixes, try `gpt-5.4-mini` / `claude-haiku-*` first.

### Lower Reasoning Effort

The higher the reasoning level, the longer the model thinks. A single `xhigh` round can be several times slower than `medium`. `medium` is sufficient for day-to-day development; enable `xhigh` only for particularly difficult problems.

Codex CLI (`~/.codex/config.toml`):

```toml
model_reasoning_effort = "medium"
```

When Claude Code uses ChatGPT models:

```bash
export CLAUDE_CODE_EFFORT_LEVEL=medium
```

### Control Context Length

The longer the context, the slower the time to first token. Run `/clear` before starting a new task, and use `/compact` promptly in long sessions.

## FAQ

**Q: Is the relay service slow?**
A: Measured relay overhead is <1 second/request, accounting for 7%. Connecting directly to the official service with the same model will not be noticeably faster.

**Q: Why is the same question sometimes fast and sometimes slow?**
A: The number of rounds varies, as does official service load. Generation time itself also has a long tail (`p99` can exceed 5× `p50`).

**Q: Does streaming make it faster?**
A: Total duration is the same, but the first token arrives sooner, so it feels faster. CLI tools use streaming by default.

**Q: Can switching networks / regions improve speed?**
A: Basically no. Network round-trip time is only a small fraction of total time; most of it is spent generating at the model provider's data center.