perf-check

name	perf-check
description	Performance impact analysis — detect O(n²) patterns, large bundle risks, unbounded data structures, and expensive operations in recent changes. Activate when #pc appears anywhere in the user message.
argument-hint	[scope-or-empty]
disable-model-invocation	false
allowed-tools	Read, Glob, Grep, Bash, Task

Analyze performance impact for: $ARGUMENTS

Phase 1 — Identify scope:

1. If a scope argument is provided, focus on those files.
2. Otherwise, inspect the current git diff (git diff HEAD and git diff --cached).
3. List all modified/added files.

Phase 2 — Pattern detection:

Use perf-analyst agent to analyze the code for:

1. Algorithmic complexity: Nested loops over collections, repeated array scans, quadratic string building.
2. Unbounded growth: Arrays/maps that grow without limits, missing pagination, uncapped caches.
3. Expensive operations: Synchronous file I/O in hot paths, unindexed database queries, N+1 query patterns.
4. Bundle impact: New large dependencies, unused imports, duplicated libraries.
5. Memory leaks: Event listeners not cleaned up, growing closures, retained references.

Phase 3 — Report:

For each finding:

[SEVERITY: HIGH|MEDIUM|LOW] file:line
Pattern: <description>
Impact: <what happens at scale>
Suggestion: <how to fix>

Phase 4 — Summary:

Performance Analysis
====================
Files analyzed: N
Findings: N (H high, M medium, L low)
Top risk: <one-liner>
Recommendation: <proceed / fix before merge / needs discussion>