Improve performance of handling skip_auto_headers

[bdraco]

What do these changes do?

Most of the time there are no auto_headers

Are there changes in behavior for the user?

no

Is it a substantial burden for the maintainers to support this?

no

before

after

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.24%. Comparing base (e058cbd) to head (5939a71).
Report is 1054 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8847   +/-   ##
=======================================
  Coverage   98.23%   98.24%           
=======================================
  Files         107      107           
  Lines       34123    34124    +1     
  Branches     4050     4050           
=======================================
+ Hits        33522    33525    +3     
+ Misses        424      423    -1     
+ Partials      177      176    -1     

Flag	Coverage Δ
CI-GHA	98.13% <100.00%> (+<0.01%)	⬆️
OS-Linux	97.79% <100.00%> (-0.01%)	⬇️
OS-Windows	96.19% <100.00%> (+<0.01%)	⬆️
OS-macOS	97.47% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	97.56% <100.00%> (+<0.01%)	⬆️
Py-3.10.14	97.49% <100.00%> (+<0.01%)	⬆️
Py-3.11.9	97.73% <100.00%> (+<0.01%)	⬆️
Py-3.12.4	95.99% <100.00%> (+<0.01%)	⬆️
Py-3.12.5	97.52% <100.00%> (-0.01%)	⬇️
Py-3.9.13	97.45% <100.00%> (+<0.01%)	⬆️
Py-3.9.19	97.39% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.16	97.00% <100.00%> (+<0.01%)	⬆️
VM-macos	97.47% <100.00%> (+<0.01%)	⬆️
VM-ubuntu	97.79% <100.00%> (-0.01%)	⬇️
VM-windows	96.19% <100.00%> (+<0.01%)	⬆️

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[patchback]

Backport to 3.10: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.10/6d9742743da6c8e07d67bc365d98110eb208cd30/pr-8847

Backported as #8904

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.11: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.11/6d9742743da6c8e07d67bc365d98110eb208cd30/pr-8847

Backported as #8905

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.