Performance

More Performance pages

Everything else tagged performance, grouped by section. Pages featured above are not repeated here.

How To

How to profile a Python script with py-spy

Record a flame graph, view it in speedscope, and attach to a running process with py-spy, the low-overhead sampling profiler for Python.

Explanation

Sampling vs deterministic profilers: which should I use?

Sampling uses timer snapshots; deterministic hooks every call. Each suits different performance questions.

Why is Python Slow?

Why Python is slower than compiled languages: dynamic type lookups, attribute resolution, and boxed values. When optimization matters.

Reference

profiling.sampling

Python 3.15's profiling.sampling: statistical sampler for running processes. Attach by PID, output flame graphs or interactive HTML.

py-spy

py-spy is a low-overhead sampling profiler for Python that attaches to a running process without code changes or restarts.