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smart_toyAI/PROMPT ENGINEERING

Shopify/liquid: Performance: 53% faster parse+render, 61% fewer allocations

sourceSimon Willison
calendar_todayMarch 13, 2026
schedule2 min read
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EXECUTIVE SUMMARY

Shopify's Liquid Engine Sees Major Performance Boost with AI-Driven Optimizations

Summary

Shopify's CEO Tobias Lütke has announced significant performance improvements to Liquid, the open-source Ruby template engine, achieving a 53% faster parse and render time along with 61% fewer memory allocations. These enhancements were made possible through a series of automated experiments using a coding agent inspired by Andrej Karpathy's autoresearch system.

Key Points

  • The performance improvements were achieved through 93 commits from approximately 120 automated experiments.
  • Key optimizations included replacing StringScanner with String#byteindex, resulting in a ~12% reduction in parse time.
  • The implementation utilized a robust test suite of 974 unit tests, facilitating effective experimentation.
  • The autoresearch pattern allowed for systematic testing of multiple potential improvements.
  • Lütke's hands-on coding approach is notable for a CEO of a large company with over 7,500 employees.
  • The coding agent used for this project is named Pi, which also has a new pi-autoresearch plugin developed in collaboration with David Cortés.
  • The improvements highlight the potential of AI-assisted programming in enhancing software performance.

Analysis

The advancements in Liquid demonstrate the effectiveness of AI-driven coding agents in optimizing legacy codebases. By leveraging automated testing and systematic experimentation, significant performance gains can be achieved, which is crucial for maintaining competitive software solutions.

Conclusion

IT professionals should consider integrating AI-assisted programming tools into their development workflows to enhance code performance and efficiency. Emphasizing robust testing frameworks will also enable more effective use of coding agents.