Elevator Pitch

• PEP 810 proposes an explicit lazy import syntax for Python that defers module loading until first use, improving startup time and memory usage while remaining fully backwards compatible and opt-in.

Key Takeaways

• The new lazy import and lazy from ... import ... syntax allow individual imports to be marked as lazy, deferring module loading until the imported name is first accessed.
• Lazy imports are local, explicit, controlled, and granular—they do not cascade, require explicit opt-in, and can be managed per-import, per-module, or globally.
• The feature is designed for incremental adoption, enabling significant performance gains (e.g., 50–70% startup time reduction) in tools, large applications, and type-annotation-heavy codebases.

Most Memorable Aspects

• Approximately 17% of imports in the Python standard library are already manually made lazy by being placed inside functions, illustrating widespread demand.
• Lazy imports use proxy objects in the namespace and avoid risky changes to Python’s core dict implementation.
• Exception tracebacks for failed lazy imports are enhanced to show both the import site and the first access, aiding debugging.

Direct Quotes

• “By allowing developers to mark individual imports as lazy with explicit syntax, Python programs can reduce startup time, memory usage, and unnecessary work.”
• “A lazy import is an isolated decision each time it is used, not a global shift in semantics.”
• “This can reduce startup time by 50-70% in practice, providing a significant improvement to a common user experience and improving Python’s competitiveness in domains where fast startup matters most.”