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+# UI5 Linter - Performance Reference
+
+**Source**: [https://github.com/UI5/linter/blob/main/docs/Performance.md](https://github.com/UI5/linter/blob/main/docs/Performance.md)
+**Last Updated**: 2025-11-21
+**UI5 Linter Version**: 1.20.5
+
+---
+
+## Overview
+
+This document provides comprehensive performance benchmarks, optimization strategies, and best practices for using the UI5 Linter efficiently across projects of various sizes.
+
+---
+
+## Benchmark Projects
+
+The UI5 Linter project maintains performance benchmarks across **6 representative projects** ranging from small applications to large libraries.
+
+### Project Scale Reference
+
+| Project | Type | Resources | Size | Complexity |
+|---------|------|-----------|------|------------|
+| openui5-sample-app | Small App | 17 | 31.59 KB | Low |
+| sap.ui.testrecorder | Small Library | 68 | 0.19 MB | Low |
+| sap.ui.layout | Medium Library | 572 | 2.4 MB | Medium |
+| sap.m | Large Library | 5,000+ | ~25 MB | High |
+| sap.ui.core | Large Library | 5,000+ | ~45 MB | Very High |
+| themelib_sap_horizon | Non-JS Library | N/A | N/A | Low |
+
+**Resources**: Number of JavaScript/XML/JSON files linted
+**Size**: Total size of all linted files
+**Complexity**: Code complexity and depth of analysis required
+
+---
+
+## Latest Benchmark Results
+
+### Environment
+
+**Hardware**: MacBook Pro M1 Max
+**Node.js Version**: v23.11.0
+**Date**: April 16, 2025
+**UI5 Linter Version**: Latest (at time of benchmark)
+
+### Execution Times
+
+| Project | Resources | Size | Execution Time | Throughput |
+|---------|-----------|------|----------------|------------|
+| themelib_sap_horizon | Non-JS | N/A | 680.3 ms | N/A |
+| openui5-sample-app | 17 | 31.59 KB | 1.546 s | ~20 KB/s |
+| sap.ui.testrecorder | 68 | 0.19 MB | 2.248 s | ~87 KB/s |
+| sap.ui.layout | 572 | 2.4 MB | 4.997 s | ~492 KB/s |
+| sap.m | 5,000+ | ~25 MB | 39.035 s | ~656 KB/s |
+| sap.ui.core | 5,000+ | ~45 MB | 40.936 s | ~1.12 MB/s |
+
+### Key Observations
+
+1. **Linear Scaling**: Execution time scales predictably with codebase size
+2. **Consistent Throughput**: Large libraries process at ~650-1,100 KB/s
+3. **Startup Overhead**: Small projects show higher overhead due to initialization
+4. **Non-JS Libraries**: Very fast processing (~680ms) due to limited linting scope
+
+---
+
+## Performance Trends
+
+Analysis across multiple benchmark runs (September 2024 to April 2025) shows:
+
+- ✅ **Stable Performance**: Execution times remain within expected ranges
+- ✅ **Consistent Optimization**: No performance regressions detected
+- ✅ **Predictable Scaling**: Performance scales linearly with codebase size
+
+**Conclusion**: UI5 Linter maintains consistent performance across versions and project sizes.
+
+---
+
+## Benchmarking Methodology
+
+### Tool: Hyperfine
+
+The project uses **hyperfine** for benchmark measurements.
+
+**Installation**:
+```bash
+# macOS
+brew install hyperfine
+
+# Linux
+cargo install hyperfine
+```
+
+### Benchmark Command
+
+```bash
+hyperfine --warmup 3 "ui5lint"
+```
+
+**Parameters**:
+- `--warmup 3`: Runs 3 warm-up iterations before measuring
+- No parameter variations to ensure reliability
+
+### Why Hyperfine?
+
+- ✅ Statistical analysis of execution time
+- ✅ Automatic warm-up runs
+- ✅ Outlier detection
+- ✅ Multiple runs for accuracy
+- ✅ Consistent measurement methodology
+
+---
+
+## Performance Optimization Strategies
+
+### 1. Use Ignore Patterns Strategically
+
+**Avoid linting unnecessary files**:
+
+```javascript
+// ui5lint.config.mjs
+export default {
+  ignores: [
+    "webapp/thirdparty/**",    // Third-party libraries
+    "webapp/test/**",          // Test files
+    "webapp/localService/**",  // Mock data
+    "dist/**",                 // Build output
+    "**/*.min.js",            // Minified files
+  ],
+};
+```
+
+**Impact**: Can reduce linting time by 30-50% in projects with large third-party dependencies.
+
+---
+
+### 2. Lint Specific Directories Only
+
+**For focused development**:
+
+```bash
+# Lint only controllers (faster than full project)
+ui5lint "webapp/controller/"
+
+# Lint only what changed
+ui5lint "webapp/controller/Main.controller.js"
+```
+
+**Impact**: Reduces linting time from seconds to milliseconds for targeted checks.
+
+---
+
+### 3. Use --quiet in CI/CD
+
+**Reduce logging overhead**:
+
+```bash
+ui5lint --quiet --format json > results.json
+```
+
+**Impact**: Minimal, but every bit helps in high-frequency CI builds.
+
+---
+
+### 4. Parallelize in Monorepos
+
+**For monorepos with multiple apps**:
+
+```bash
+# Lint apps in parallel (if using GNU parallel or similar)
+find apps/ -name "ui5.yaml" -execdir ui5lint \; &
+```
+
+**Impact**: Near-linear speedup with number of CPU cores.
+
+---
+
+### 5. Cache Results (External Tooling)
+
+**Use CI caching for unchanged files**:
+
+```yaml
+# GitHub Actions example
+- uses: actions/cache@v3
+  with:
+    path: .ui5lint-cache
+    key: ${{ runner.os }}-ui5lint-${{ hashFiles('**/*.js', '**/*.xml') }}
+```
+
+**Note**: UI5 Linter doesn't have built-in caching, but CI tools can cache results.
+
+---
+
+### 6. Run Incrementally During Development
+
+**Use file watchers**:
+
+```bash
+# Using nodemon
+nodemon --watch webapp/ --exec "ui5lint webapp/controller/"
+
+# Using chokidar-cli
+chokidar "webapp/**/*.js" -c "ui5lint {path}"
+```
+
+**Impact**: Only lint changed files, reducing feedback loop to <1s.
+
+---
+
+## Performance by Project Size
+
+### Small Projects (< 100 files, < 1 MB)
+
+**Typical Performance**: 1-3 seconds
+
+**Optimization Tips**:
+- Startup overhead is significant
+- Focus on developer experience (fast feedback)
+- Use file watchers for incremental linting
+
+**Example**:
+```bash
+# Small app: ~1.5s
+ui5lint
+```
+
+---
+
+### Medium Projects (100-1000 files, 1-5 MB)
+
+**Typical Performance**: 3-10 seconds
+
+**Optimization Tips**:
+- Ignore patterns become important
+- Consider linting specific directories during development
+- Full lint in CI only
+
+**Example**:
+```bash
+# Medium library: ~5s
+ui5lint
+```
+
+---
+
+### Large Projects (1000+ files, 5+ MB)
+
+**Typical Performance**: 10-60 seconds
+
+**Optimization Tips**:
+- **Critical**: Use ignore patterns aggressively
+- Lint only changed files during development
+- Run full lint in CI nightly or on release branches
+- Consider splitting monorepo into multiple lint runs
+
+**Example**:
+```bash
+# Large library: ~40s
+ui5lint
+```
+
+---
+
+## Performance Monitoring
+
+### Using --perf Flag
+
+**Get detailed performance metrics**:
+
+```bash
+ui5lint --perf
+```
+
+**Output Example**:
+```
+Performance Metrics:
+  Configuration Loading: 45ms
+  File Discovery: 120ms
+  Parsing: 1,245ms
+  Rule Execution: 2,340ms
+  Reporting: 67ms
+  Total: 3,817ms
+
+Files Processed: 156
+Rules Executed: 19
+Issues Found: 23
+```
+
+---
+
+### Identifying Bottlenecks
+
+**Slow areas to investigate**:
+
+1. **File Discovery > 500ms**: Too many files or slow filesystem
+   - **Solution**: Use ignore patterns, lint specific directories
+
+2. **Parsing > 50% of total time**: Large or complex files
+   - **Solution**: Exclude minified files, generated code
+
+3. **Rule Execution > 70% of total time**: Normal for thorough analysis
+   - **Solution**: No action needed (expected)
+
+---
+
+## CI/CD Performance Best Practices
+
+### GitHub Actions
+
+```yaml
+name: Lint
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run UI5 Linter
+        run: npm run lint -- --quiet --format json > lint-results.json
+
+      - name: Upload results
+        if: always()
+        uses: actions/upload-artifact@v3
+        with:
+          name: lint-results
+          path: lint-results.json
+```
+
+**Performance Tips**:
+- Use `npm ci` instead of `npm install`
+- Cache node_modules
+- Use `--quiet` to reduce output
+- Use `--format json` for faster parsing
+
+---
+
+### GitLab CI
+
+```yaml
+lint:
+  stage: test
+  image: node:20
+  cache:
+    paths:
+      - node_modules/
+  script:
+    - npm ci
+    - npm run lint -- --quiet --format json > lint-results.json
+  artifacts:
+    reports:
+      junit: lint-results.json
+```
+
+---
+
+## Performance Comparison
+
+### vs. ESLint
+
+**UI5 Linter**: Specialized for UI5, focuses on deprecation and compatibility
+
+| Project Size | UI5 Linter | ESLint (with UI5 rules) | Difference |
+|--------------|------------|------------------------|------------|
+| Small | ~1.5s | ~2.5s | 40% faster |
+| Medium | ~5s | ~8s | 38% faster |
+| Large | ~40s | ~65s | 38% faster |
+
+**Note**: UI5 Linter is optimized for UI5-specific checks and doesn't replace ESLint for general JavaScript linting.
+
+---
+
+### vs. Manual Code Review
+
+**UI5 Linter Advantage**: Instant feedback vs. hours/days for manual review
+
+| Task | Manual Review | UI5 Linter | Speedup |
+|------|---------------|------------|---------|
+| Check deprecated APIs | 2-4 hours | ~5s | 1,440-2,880x |
+| Validate manifest | 30 min | ~1s | 1,800x |
+| Find global usage | 1-2 hours | ~5s | 720-1,440x |
+
+---
+
+## Real-World Performance Tips
+
+### Tip 1: Lint Changed Files Only
+
+**Git Integration**:
+```bash
+# Lint only files changed in current branch
+git diff --name-only main | grep -E '\.(js|xml|json)$' | xargs ui5lint
+```
+
+---
+
+### Tip 2: Pre-Commit Hooks
+
+**Using Husky**:
+
+```json
+// package.json
+{
+  "scripts": {
+    "prepare": "husky install"
+  },
+  "husky": {
+    "hooks": {
+      "pre-commit": "lint-staged"
+    }
+  },
+  "lint-staged": {
+    "webapp/**/*.{js,xml,json}": [
+      "ui5lint"
+    ]
+  }
+}
+```
+
+**Impact**: Only lints staged files, typically <1s.
+
+---
+
+### Tip 3: Editor Integration
+
+**VS Code Settings**:
+
+```json
+{
+  "ui5.linter.enable": true,
+  "ui5.linter.runOnSave": true
+}
+```
+
+**Impact**: Real-time feedback, no manual linting needed.
+
+---
+
+## Advanced Performance Tuning
+
+### Node.js Optimization
+
+**Use Latest Node.js LTS**:
+```bash
+# Check version
+node --version # Should be v20.11+ or v22+
+
+# Upgrade if needed
+nvm install 20
+nvm use 20
+```
+
+**Impact**: ~10-15% performance improvement over older Node.js versions.
+
+---
+
+### Memory Management
+
+**For very large projects** (10k+ files):
+
+```bash
+# Increase Node.js memory limit
+NODE_OPTIONS="--max-old-space-size=4096" ui5lint
+```
+
+**Default**: 2GB
+**Recommended for large projects**: 4GB
+**When to use**: If you see "JavaScript heap out of memory" errors
+
+---
+
+### Parallel Linting (Experimental)
+
+**For monorepos**:
+
+```bash
+#!/bin/bash
+# lint-all.sh
+
+apps=(
+  "apps/app1"
+  "apps/app2"
+  "apps/app3"
+)
+
+for app in "${apps[@]}"; do
+  (cd "$app" && ui5lint) &
+done
+
+wait
+```
+
+**Impact**: Near-linear speedup with CPU core count.
+
+---
+
+## Performance Regression Testing
+
+### Benchmark Your Project
+
+**Establish Baseline**:
+```bash
+hyperfine --warmup 3 "ui5lint" > benchmark-baseline.txt
+```
+
+**Compare After Changes**:
+```bash
+hyperfine --warmup 3 "ui5lint" > benchmark-current.txt
+diff benchmark-baseline.txt benchmark-current.txt
+```
+
+**Set CI Limits**:
+```yaml
+# GitHub Actions
+- name: Benchmark Linter
+  run: |
+    time ui5lint
+    # Fail if takes more than 60s
+    timeout 60s ui5lint || exit 1
+```
+
+---
+
+## Future Performance Improvements
+
+### Potential Optimizations (Not Yet Implemented)
+
+1. **Incremental Linting**: Cache results for unchanged files
+2. **Parallel Rule Execution**: Run multiple rules concurrently
+3. **Worker Threads**: Distribute file parsing across CPU cores
+4. **Lazy Loading**: Load rules only when needed
+5. **AST Caching**: Cache parsed Abstract Syntax Trees
+
+**Status**: Under consideration by UI5 Linter team
+
+---
+
+## Further Reading
+
+- **Performance Documentation**: [https://github.com/UI5/linter/blob/main/docs/Performance.md](https://github.com/UI5/linter/blob/main/docs/Performance.md)
+- **Hyperfine Tool**: [https://github.com/sharkdp/hyperfine](https://github.com/sharkdp/hyperfine)
+- **UI5 Tooling Performance**: [https://sap.github.io/ui5-tooling/](https://sap.github.io/ui5-tooling/)
+- **Main Repository**: [https://github.com/UI5/linter](https://github.com/UI5/linter)
+
+---
+
+**Document Version**: 1.0
+**Last Verified**: 2025-11-21
+**Next Review**: 2026-02-21