0.5.2

Performance Improvements

StaxXmlWriter Optimization (+31.7% average improvement)

The XML Writer(sync/async both) has been significantly optimized through three key algorithmic improvements:

1. Regex Caching (+9.3%)

   • Static readonly patterns for basic XML entities
   • Construction-time compilation for custom entities
   • Eliminates repeated regex creation overhead

2. Attribute String Batching (+36.5%)

   • Single string concatenation before write operation
   • Reduces function call overhead from 4 calls to 1 per attribute
   • Exceptional improvement in attribute-heavy documents

3. Early Entity Check (+25.6%)

   • Fast string.includes() checks before regex operations
   • Avoids expensive regex when no entities are present
   • Significant performance gain for clean text content

Benchmark Results (50,000 elements):

• Realistic documents: +18.4% (180ms → 147ms)
• Mixed content: +54.1% (99ms → 46ms)
• Deep nested structures: +63.8% (86ms → 31ms)
• Attribute-heavy: +35.8%

All optimizations maintain 100% API compatibility and pass all 796 test cases with identical output.

StaxXmlParserSync Optimization (+20.67% improvement)

Replaced generator-based implementation with a state machine approach:

Key Improvements:

• Eliminated generator overhead (~95ns → ~10ns per event)
• IteratorResult object reuse (zero allocations)
• Pending event queue for self-closing tag handling
• 95%+ code reuse from existing parsing logic

Benchmark Results (10MB XML file):

• Generator baseline: 115.98ms
• State machine: 92.00ms
• Improvement: +20.67%

StaxXmlParser (Async) Optimization (~15% improvement)

Replaced Array-based queue with a circular buffer implementation:

Key Improvements:

• Eliminated O(n) Array.shift() operations → O(1) dequeue
• Improved memory locality with circular buffer pattern
• Queue operation cost reduced from 50ns to 10ns
• Dynamic queue growth when needed

Benchmark Results (1GB XML file):

• Array-based queue: baseline
• Circular buffer: ~15% faster
• All 796 tests passed with 100% API compatibility

Changed

• Writer performance improved by 20-60% depending on XML structure
• Sync parser performance improved by 20.67%
• Async parser performance improved by ~15% on large files

Technical Details

For detailed performance analysis and benchmarking methodology, see:

• Writer optimization: packages/benchmark/writer-optimization/results/FINAL-ANALYSIS.md
• Parser optimization: packages/benchmark/PARSER_OPTIMIZATION_FINAL_REPORT.md

Internal

• Removed unused internal methods
• Enhanced benchmarking infrastructure
• Comprehensive documentation of optimization attempts and learnings

v0.4.0

Performance Improvements:

• Optimization for V8 hidden class
• StaxXmlParserSync: unnecessary substring operations removed
• Caching entity regex for better performance
• Inline functions to reduce function call overhead

API Changes:

• Breaking: StaxXmlWriter is now async-based, synchronous version moved to StaxXmlWriterSync

Documentation & Testing:

• Added documentation using Astro Starlight
• Added several performance benchmarks

Major performance improvements and breaking changes for better async handling.