TL;DR
PEP 810 introduces optional lazy keyword for imports, enabling 50-80% startup time improvements for CLI tools without breaking existing code.
Key Points
- Instagram achieved 50-80% startup time improvements and 40-90% memory reductions using lazy imports in production
- Hudson River Trading migrated entire firm to lazy-by-default Python, reducing multi-minute startup times to seconds
- PEP 810 uses explicit opt-in syntax (lazy import json) with proxy-based implementation, avoiding dict internals changes that blocked PEP 690
- Steering Council unanimously approved PEP 810 on November 3, 2025; feature ships in Python 3.15 (October 2026)
Why It Matters
Lazy imports solve a real pain point for large Python codebases without fragmenting the ecosystem. Developers can now opt-in to deferred module loading on a per-import basis, dramatically improving CLI responsiveness and reducing memory overhead—all with a single keyword and no code restructuring. This addresses why Meta and HRT felt compelled to fork CPython internally.
Source: techlife.blog