optimize

name	optimize
description	Analyzes code for performance bottlenecks and produces prioritized, actionable optimization recommendations with before/after code. Use before shipping performance-critical features or when code feels slow.
argument-hint	[file, function, or 'all' for project-wide scan]
allowed-tools	Read, Grep, Glob, Bash

Performance Optimization Analysis

Project Context

!ls package.json requirements.txt go.mod Cargo.toml *.csproj pom.xml 2>/dev/null !wc -l $(find . -type f \( -name "*.ts" -o -name "*.js" -o -name "*.py" -o -name "*.go" -o -name "*.rs" -o -name "*.java" -o -name "*.cs" -o -name "*.rb" \) -not -path "*/node_modules/*" -not -path "*/.git/*" -not -path "*/vendor/*" 2>/dev/null | head -5) 2>/dev/null | tail -1

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Analysis Categories

Examine the specified code for issues in each category. For every issue found:

1. Show the problematic code snippet (with file:line)
2. Explain why it's a problem with complexity analysis
3. Show the optimized version
4. Rate impact: High / Medium / Low

1. Algorithmic Complexity

• O(n²) or worse loops that can be reduced
• Redundant iterations over the same data
• Sorting in loops (sort once, iterate many)
• Nested loops that can be replaced with hash maps/sets
• Unnecessary full-collection scans when early exit is possible

2. Database & I/O

• N+1 query patterns (loop of individual queries instead of batch)
• Missing database indexes for frequent queries
• Unbounded queries without LIMIT/pagination
• Sequential I/O that could be parallelized
• Missing connection pooling
• Redundant file reads (read once, use many)

3. Memory & Allocation

• Large object copies that could use references/pointers
• String concatenation in loops (use builder/buffer)
• Accumulating data in memory that could be streamed
• Memory leaks: event listeners not removed, subscriptions not cancelled
• Caching opportunities for expensive computations

4. Concurrency & Async

• Sequential await calls that could use Promise.all / asyncio.gather / goroutines
• Blocking the main thread/event loop with CPU-heavy work
• Missing cancellation for abandoned async operations
• Thread-safety issues with shared mutable state

5. Language-Specific

JavaScript/TypeScript:

• Unnecessary re-renders (missing React.memo, useMemo, useCallback)
• Barrel imports pulling in entire modules
• Missing tree-shaking opportunities
• Synchronous operations that should be async

Python:

• Using lists where sets/dicts provide O(1) lookup
• Not using generators for large sequences
• Global interpreter lock (GIL) bottlenecks
• Missing __slots__ for memory-heavy classes

Go:

• Unnecessary goroutine creation
• Unbuffered channels causing blocking
• Excessive garbage collection from short-lived allocations

General:

• Missing HTTP caching headers
• Uncompressed API responses
• Missing lazy loading for heavy resources

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Output Format

Findings Table

#	File:Line	Issue	Impact	Category
1	...	...	High	...

Detailed Findings

For each finding, show before/after code.

Top 3 Priority Actions

Rank the three most impactful optimizations to implement first, with estimated effort (S/M/L) and expected improvement.