priority: high

PyO3 Performance Patterns

Use pyo3_async_runtimes for async Python callbacks (~28x faster than spawn_blocking for fast ops).

Pattern: Check __await__ attribute, use pyo3_async_runtimes::tokio::into_future() for async, fallback to spawn_blocking for sync. Release GIL before awaiting. Use Python::attach() not with_gil().

spawn_blocking for long ops (OCR), block_in_place for quick ops (PostProcessor/Validator). CRITICAL: spawn_blocking on PostProcessor/Validator causes GIL deadlocks.

Reference: crates/kreuzberg-py/README.md