speedupskill

Applies measured techniques to reduce web and Electron app load time and input latency.

152|13|Updated Aug 21, 2026
One-click install
npx skills add https://github.com/jjcm/makefaster --skill speedupskill-jjcm
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: speedupskill
Source: https://github.com/jjcm/makefaster/tree/main/skill
Command: npx skills add https://github.com/jjcm/makefaster --skill speedupskill-jjcm

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Web and Electron apps often ship with slow first paint, bloated JavaScript bundles, oversized images, and input jank, and generic performance advice rarely tells you which fix actually moves LCP, TBT, or keystroke latency. This Skill provides a catalog of techniques proven in measured speed labs, each with attributed before/after numbers and explicit anti-patterns. ## Core Features & Use Cases - Measured technique catalog: Covers boot payload embedding, critical JS graph reduction, content-hash caching, image srcset ladders, cache header rules, and O(n) paste parsing, each with real millisecond deltas. - Anti-pattern guardrails: A lab-proven "what not to do" table lists tempting changes (preloading thumbnails, fetchpriority hints, immutable derivative caching) that measured worse or caused regressions. - Keep/ditch discipline: Scores every iteration on speed, complexity, and maintainability before anything is proposed for the main branch. - Use Case: A developer profiling a slow SPA uses the catalog to embed route-scoped boot payloads, split the JS graph to the first view, and cap image srcset rungs to the CSS slot, verifying each change against a measured noise floor. ## Quick Start Ask the agent to speed up your web app's load time using the measured techniques in this skill, starting with profiling a user-felt metric like LCP.

Frequently Asked Questions about speedupskill

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I speed up a slow web app first paint?

Measure a user-felt metric like LCP first, then cut the critical JS graph to the first view and embed only the API payloads the current route reads in the first paint. The catalog shows these changes taking routes from ~2.6 s to under 400 ms in real labs.

What techniques reduce JavaScript bundle load time?

Route-gated dynamic imports, route-aware modulepreload hints, per-section settings splits, and extracting single-route whales reduced boot JS from 2651 KB to 147-178 KB. Content-hashed URLs with immutable caching eliminate warm-load revalidation requests entirely.

Does preloading images improve LCP?

No, lab measurements showed preloading grid thumbnails made pages slower, with slow4g LCP nearly doubling from 2444 to 4028 ms. Images steal connections from render-critical JS and CSS, so this change was reverted.

How do I fix input lag when pasting large text in Electron?

Replace quadratic parsing with linear algorithms, window typeahead scans to 256 characters before the caret, and defer decoration rebuilds on large documents. These changes cut a 1 MB paste parse from 2059 ms to 11.6 ms.

When should I not use immutable cache headers?

Avoid immutable caching on parameter-dependent derivatives like resized thumbnails, because a retune never reaches returning visitors. Use bounded max-age instead, and only set cache headers at WriteHeader time on 2xx/3xx responses so errors never cache.