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Python 3.13’s Big Bet: Free-Threading (No-GIL Mode) + an Experimental JIT

PEP 703 free-threaded builds and PEP 744 JIT land as experiments. Start checking thread-safety now.

5 min read Updated 2025

Python 3.13 surfaces the future: optional no-GIL builds and an experimental JIT. C extensions need thread-safety reviews, and performance gains depend on workload.

Throughput vs threads

Action: track dependency readiness, and benchmark with/without JIT for your workloads.

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