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 agentmods add skills/loiane/specs-driven-development-spring-angular/performance-optimizationnpx skills add loiane/specs-driven-development-spring-angular --skill performance-optimizationgit clone --depth 1 https://github.com/loiane/specs-driven-development-spring-angularWhat 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 | $0.00089 | $0.02614 |
| Opus 5 | $0.00044 | $0.01307 |
| Sonnet 5 | $0.00018 | $0.00523 |
| Haiku 4.5 | $0.00009 | $0.00261 |
Grade A, and why
performance-optimization 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 yesterday.
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 — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Performance optimization (Spring Boot 4 / JVM)
Rule zero: measure first
No optimization without a profile or a benchmark. "It feels slow" is a hypothesis, not a finding.
If a PR labeled perf lands without a profile artifact, a JMH result, a flame graph, or a before/after metric screenshot, request changes. The artifact path goes in the PR description and in 05-implementation-log.md.
Acceptable evidence:
- async-profiler flame graph (CPU or alloc) saved as SVG/HTML.
- JDK Flight Recorder recording (
.jfr) with the relevant view captured. - JMH benchmark output (
*.jsonfrom-rf json) with before/after. - Micrometer histogram screenshots (p50/p95/p99) from before and after.
- Database
EXPLAIN ANALYZEoutput for the query in question.
SLO-first, not optimization-first
Every perf claim is tied to a Service Level Objective. If there is no stated SLO, the work has no exit criterion — write the SLO first.
Template (the user fills the blanks; never invent the numbers):
Endpoint: <method> <path>
p50 latency: ___ ms (current: ___ ms)
p95 latency: ___ ms (current: ___ ms)
p99 latency: ___ ms (current: ___ ms)
Throughput: ___ rps (current: ___ rps)
Error budget: ___ % (window: ___ )
Measurement: <Micrometer metric name + dashboard link>
If the user has not committed to numbers, file a Q-NNN in 01-spec.md or 03-design.md and halt.
Tools
| Tool | Use for | Notes |
|---|---|---|
| async-profiler | CPU and allocation flame graphs in production-like envs | -e cpu or -e alloc; safe in prod (sample-based) |
| JFR + JDK Mission Control | Always-on low-overhead recording; method profiling, allocation, GC, locks | Enable with -XX:StartFlightRecording=... |
| JMH | Microbenchmarks for hot loops, parsers, serialization, comparator/equality changes | Fork ≥ 2, warmup ≥ 5, measure ≥ 5; run on the deploy hardware class |
| Micrometer + Spring Boot Actuator | Production metrics (latency histograms, throughput, error rate) | Use Timer with publishPercentileHistogram(true); not Counter for latency |
EXPLAIN ANALYZE |
Real query plan with row counts, buffers, timing | PostgreSQL: EXPLAIN (ANALYZE, BUFFERS, VERBOSE) ... |
-Djdk.tracePinnedThreads=full |
Detect virtual-thread pinning during dev/test | Enable in test profiles when investigating throughput regressions |
-Xlog:gc* or JFR GC events |
GC pause analysis | Look at p99 pause, not average |
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.
- yesterday First seen · 164 lines · 89 tokens per session scan A 06b7478c0468
performance-optimization is a skill published in the GitHub repository loiane/specs-driven-development-spring-angular (57 stars, last pushed 2mo ago), licensed MIT. It adds 89 tokens to every session and 2,614 once invoked, about $0.0004 per session on Opus 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 2026-08-30.
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