| name | perf |
| description | Before/after performance benchmarking comparing current branch against base, with statistical analysis. Use for benchmarking, profiling, or measuring performance impact. |
| disable-model-invocation | true |
| allowed-tools | Bash(bash ~/.claude/skills/perf/scripts/perf.sh:*), Bash(bash agents/skills/perf/scripts/perf.sh:*) |
Performance Benchmark
Run a command multiple times on the current branch and the base branch, then compare with statistical analysis.
Arguments
$ARGUMENTS - Required: the command to benchmark (e.g., "go test -bench=. ./pkg/..." or "npm run build"). Optional: --runs <count> for number of runs (default 5), --base <ref> to override base branch.
Context
- Current branch: !
git branch --show-current
- Base ref: !
git branch -r 2>/dev/null | grep -oE 'origin/(main|master)' | head -1
- Git status: !
git status --short
Your task
Run before/after benchmarks comparing the current branch against the base branch.
Step 1: Parse arguments and run the benchmark script
Extract the benchmark command and optional flags (--runs N, --base <ref>) from $ARGUMENTS.
IF no command is provided, ask: "What command should I benchmark?"
Resolve the script path — use the first that exists:
~/.claude/skills/perf/scripts/perf.sh (deployed via symlink)agents/skills/perf/scripts/perf.sh (repo-relative, for development/workspaces)
bash <script-path> "<command>" [--runs N] [--base <ref>]
Handle the exit code:
- Exit 0 — Format the output as the report below and show it as your final response.
- Exit 1 — Report the error from stderr.
- Exit 2 — Report: "Benchmark command failed. Verify the command works:
<command>"
Step 2: Format the report
Parse the script's structured output and present it as:
## Benchmark Results
**Command:** `<command>`
**Runs:** <N> (+ 1 warmup)
### Timing
| Metric | Base (<ref>) | Current (<branch>) | Delta |
|--------|-------------|-------------------|-------|
| Min | <X>s | <Y>s | <diff> |
| Max | <X>s | <Y>s | <diff> |
| Mean | <X>s | <Y>s | <diff> |
| Median | <X>s | <Y>s | <diff> |
| Stddev | <X>s | <Y>s | — |
### Raw Data
**Base:** <comma-separated times>
**Current:** <comma-separated >
<1-2 sentence explanation>
If the script output includes a high-variance warning, append it after the verdict.
