Improve startup overhead #884

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1. ofek

   added sub-issues on Oct 20, 2025

   • Add CI gate for non-trivial regressions in startup time #885
   • Profile startup time to find hotspots #886
   • Investigate lazily importing typing module #887
2. ofek commented on Jun 21, 2026

   

   ofek

   on Jun 21, 2026

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   When it comes time to start robustly tracking this, I strongly recommend that we use hyperfine to measure the true overhead by computing the delta of the interpreter startup time.

   ❯ (
       uv run --python 3.14 --no-project --isolated --with msgspec
       -- hyperfine
           --export-json -
           --style none
           --shell none
           --min-runs 100
           --warmup 10
           --reference-name baseline
           --reference 'python -c pass'
           --command-name combined
           'python -c "import msgspec"'
       err> null-device
       | from json
       | get results
       | select command median
       | update median {|r| $r.median * 1000}
       | transpose --header-row --as-record
       | insert overhead {|r| $r.combined - $r.baseline}
   )
   ╭──────────┬───────╮
   │ baseline │ 47.02 │
   │ combined │ 87.67 │
   │ overhead │ 40.65 │
   ╰──────────┴───────╯

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