Performance skills for Codex
Skills for making software measurably faster: Core Web Vitals and Lighthouse, bundle and image weight, React render profiling, CPU and heap profiling for Node, Python, Go and the JVM, flame graphs, memory leaks, HTTP caching, latency budgets and regression gates in CI.
curl -fsSL codexskills.dev/install.sh | sh -s -- --category performance Installs all 20 into ~/.agents/skills/. Or download the zip.
All 20 Performance skills
Each opens the full SKILL.md, example prompts and every way to install it.
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Bundle Size Reduction
Find the kilobytes that matter and cut them -
Code Splitting
Load each route's code, prefetch the next one -
Core Web Vitals
Fix the LCP, INP or CLS phase that actually dominates -
Database Performance Triage
Is it the query, the pool, the locks or the app? -
CPU Flame Graphs
Sampled stacks, real symbols, the wide frame named -
Go pprof Profiling
Right profile, right line, benchstat proof -
HTTP Caching Headers
Cache assets for a year, HTML for zero seconds -
Image Optimization
Smaller images, same pixels, faster hero -
JVM Tuning
Collector, heap size, logs: short flags, real data -
Latency Budgets
Split p99 across every hop, then set timeouts -
Lighthouse Audits
Median-of-five runs and CI assertions that hold -
Memory Leak Hunting
Snapshot, repeat, compare, follow the retainer -
Node.js Profiling
Classify the slowdown, then profile the right thing -
Performance Budgets
Regression gates that fail for real, not for noise -
Python Profiling
cProfile, py-spy or memray: the right one first -
React Render Profiling
Record the lag, read why it rendered, fix that -
Real User Monitoring
Field Web Vitals that point at the culprit -
Third-Party Scripts
Price every tag, then load it only when needed -
TTFB Optimization
Split server response time, then cut the big slice -
Web Workers
Heavy work off the main thread, UI stays responsive
No Performance skill matches that.
Where to start
Install the ones that match requests you make every week. Name one with $core-web-vitals when you want it for sure; otherwise Codex picks by description.
Start with
- Core Web VitalsFix the LCP, INP or CLS phase that actually dominates
- Bundle Size ReductionFind the kilobytes that matter and cut them
- Code SplittingLoad each route's code, prefetch the next one
Install a few by name
curl -fsSL codexskills.dev/install.sh | sh -s -- bundle-size-reduction code-splitting 104-line POSIX script. No sudo, no telemetry. Read install.sh
Performance FAQ
How do I install every Performance skill at once?
Run curl -fsSL https://codexskills.dev/install.sh | sh -s -- --category performance to put all 20 in ~/.agents/skills/, or add --project to install them into the current repository's .agents/skills/. You can also download the category zip and unpack it yourself.
Does installing 20 skills slow Codex down?
Hardly. At startup Codex sees only each skill's name and description, a few dozen words apiece, and reads a full SKILL.md only when a task needs it. Install the whole category if the work fits; unused skills cost almost nothing.
Which Performance skill should I start with?
Start with Core Web Vitals, Bundle Size Reduction, Code Splitting. They cover the requests that come up most in this category. Mention one with $core-web-vitals to try it.