Summary
On July 21, 2026 Vercel began precompiling Python function code and dependencies to bytecode at build time, so cold starts skip on-demand compilation and Python functions start faster.
What changed
Vercel now precompiles Python application code and dependencies to bytecode during the build, removing compilation work from cold-start time.
Why it matters
Faster Python cold starts matter for AI backends and agent tools that lean on Python for inference glue and data work, where per-invocation latency shapes user experience. It narrows a long-standing gap between Python and JavaScript serverless performance on Vercel.
Evidence excerpt
Python functions on Vercel now start faster. Application code and dependencies are precompiled to bytecode at build time, so cold starts skip compilation.