Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add oborchers/fractional-cto --skill speed-is-the-featuregit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/oborchers/fractional-cto/speed-is-the-feature)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/speed-is-the-feature"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/speed-is-the-feature/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/oborchers/fractional-cto/speed-is-the-feature"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/speed-is-the-feature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00060 | $0.00793 |
| Opus 5.5 | $0.00024 | $0.00317 |
| Sonnet 5.5 | $0.00012 | $0.00159 |
| Haiku 4.5 | $0.00006 | $0.00079 |
Grade A, and why
speed-is-the-feature scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Speed Is the Feature
Speed is not an optimization — it is the product. Linear built a billion-dollar company on this insight. Every architectural decision should serve Nielsen's three perception thresholds.
The Three Thresholds
| Threshold | Perception | Target For |
|---|---|---|
| 100ms | Instantaneous — feels caused by the user | Toggles, selections, navigating between loaded views |
| 1 second | Flow uninterrupted — user feels in control | Page transitions, data loads |
| 10 seconds | Attention limit — user wants to multitask | Show percent-done indicator or lose them |
Core Principle: Decouple Feedback from the Network
The UI must respond before the server confirms. This does not require a local-first architecture — it requires separating the feedback loop from network latency.
Optimistic UI
Update the UI immediately on user action. Reconcile with the server in the background.
When to use optimistic updates:
- Simple, binary-like actions (like, toggle, send, favorite)
- Actions with a success rate exceeding 97%
- Client-side validation passes before sending
Rules:
- Always handle failure gracefully — revert state and explain what happened
- Validate inputs client-side before the optimistic update
- Never use optimistic UI to mask genuinely slow operations — fix the operation instead
Skeleton Screens
Skeleton screens beat spinners, but only when done correctly.
Research findings (Bill Chung):
- Left-to-right shimmer animation is perceived as shorter than pulsing opacity
- Slow, steady motion beats fast motion
- Skeleton elements must match actual content layout — a skeleton showing only header and footer is functionally a spinner
When to use which loading indicator:
| Load Duration | Indicator |
|---|---|
| < 1.5 seconds | Nothing, or a subtle spinner |
| 1.5–10 seconds | Skeleton screen with shimmer |
| > 10 seconds | Percent-done progress bar |
Performance Budget
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 5d ago First seen · 82 lines · 60 tokens per session scan A 7a34d200e313
speed-is-the-feature is a skill published in the GitHub repository oborchers/fractional-cto (32 stars, last pushed 5d ago), licensed MIT. It adds 60 tokens to every session and 793 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-13.
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