Mode d’emploi
- Copiez la commande et examinez le paquet avant de l’installer dans votre environnement agent.
- Consultez le document original pour les outils, identifiants et environnements requis.
- Décrivez les entrées et le livrable souhaité ; comparez la sortie aux sources.
npx skills add https://github.com/daveebbelaar/bama --skill performanceAvant de commencer
- L’installation n’inclut ni abonnement au modèle, ni quota API, ni accès aux fichiers.
- Étoiles et installations reflètent l’activité, pas un test indépendant de qualité ou de sécurité.
Rendu depuis le dépôt source en conservant titres, exemples, code, tableaux, liens et images.
Performance
Fast means two numbers: the first frame after a key press shows in under 100 ms, and nothing on the main thread blocks for more than 50 ms. Every change in this skill starts and ends with a measurement, so you know it helped. Symptom-by-symptom fixes are in recipes.md. For video, audio, camera, Metal, or large image pipelines, also read gpu-media.md.
The loop
reproduce -> measure (release build) -> find the line -> fix -> measure again -> commit with the numbers- Reproduce. Write the exact steps, or add a probe command to the
debug bridge (test-mac-app skill) that runs the slow action and logs the time of each step.
- Measure the release build. Debug Swift is 3 to 10 times slower and
points at the wrong code.
- Find the line. Pick the tool for the symptom:
| Symptom | Tool |
|---|---|
| App freezes, spinning pointer | sample <App> 5, then read the main thread stack |
| Slow action | Time Profiler: xcrun xctrace record --template 'Time Profiler' --attach <App> --time-limit 10s |
| Short freezes while typing or dragging | --template 'Hangs' |
| Stutter while moving or animating | --template 'Animation Hitches' |
| Memory grows | footprint <App>, leaks <App>, --template 'Allocations' |
| Fan, battery | --template 'Energy Log', look for timers and polling |
Read traces as text, not in the Instruments GUI: see "Measuring" in recipes.md. Delete every .trace after reading. A trace stores the app's full environment, and an app opened from an agent's shell inherits that shell's tokens. Never commit or share one.
- Fix with the matching recipe.
- Measure again with the same steps. Put before and after in the
commit message: "Picker opens in 40 ms, was 600 ms".
The rules that fix most problems
- Main thread does UI only. File, network, database, image decoding,
Accessibility calls, and audio go elsewhere. A main-thread call that waits on another process (CoreAudio, AX) can freeze the app for minutes.
- Show first, work after. Put the window or panel on screen in the same
frame as the key press, then load. Never make the UI wait for the work.
- Let the GPU composite. Large images go in a
CALayeronce. Pointer
movement changes only small layers. Never redraw a full-screen picture per mouse event.
- Decode at display size. ImageIO thumbnails, cached in
NSCache. - Do not animate what must be fast. Search results and switchers
update in place.
- No polling without a reason. Timers get a tolerance and stop when
nothing on screen needs them.
Apple silicon notes
- Core Animation, Core Image (one shared
CIContext), Vision, and
AVFoundation already run on the GPU or the Neural Engine. Hand them the work instead of looping over pixels in Swift.
- Write Metal (
MTKView, compute shaders) only when a measurement shows
Core Animation or Core Image is too slow. Most apps never need it.
- Unified memory means a
CGImagefrom ScreenCaptureKit passes to a layer
without a copy. Keep it as a CGImage or IOSurface. Converting to NSImage and back costs copies.
Done when the slow action has a measured before and after, the after meets the two numbers at the top, and the commit message names both.
