[PR #13362/d041d4d0 backport][3.15] Fix excessive CPU use on decompressing small members

[patchback]

This is a backport of PR #13362 as merged into master (d041d4d).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.28%. Comparing base (2c4479f) to head (f90d48b).
⚠️ Report is 2 commits behind head on 3.15.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff            @@
##             3.15   #13392    +/-   ##
========================================
  Coverage   98.28%   98.28%            
========================================
  Files         136      136            
  Lines       49549    49713   +164     
  Branches     2676     2682     +6     
========================================
+ Hits        48698    48861   +163     
  Misses        672      672            
- Partials      179      180     +1     

Flag	Coverage Δ
CI-GHA	98.29% <100.00%> (+<0.01%)	⬆️
OS-Linux	98.06% <100.00%> (+<0.01%)	⬆️
OS-Windows	95.74% <97.46%> (+0.01%)	⬆️
OS-macOS	97.22% <97.46%> (-0.01%)	⬇️
Py-3.10	97.40% <100.00%> (+<0.01%)	⬆️
Py-3.11	97.69% <100.00%> (+<0.01%)	⬆️
Py-3.12	97.77% <100.00%> (+<0.01%)	⬆️
Py-3.13	97.75% <100.00%> (+<0.01%)	⬆️
Py-3.14	97.86% <100.00%> (+0.01%)	⬆️
Py-3.14t	96.85% <97.43%> (+<0.01%)	⬆️
Py-pypy-3.11	96.68% <92.89%> (+0.01%)	⬆️
VM-macos	97.22% <97.46%> (-0.01%)	⬇️
VM-ubuntu	98.06% <100.00%> (+<0.01%)	⬆️
VM-windows	95.74% <97.46%> (+0.01%)	⬆️
cython-coverage	38.67% <48.73%> (+0.02%)	⬆️

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[codspeed-hq]

Merging this PR will improve performance by 9.46%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 83 untouched benchmarks
⏩ 86 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_send_one_hundred_websocket_text_messages[pyloop]	1.9 ms	1.8 ms	+9.46%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing patchback/backports/3.15/d041d4d0fd48c3f0832084d33be16cf1c4835f85/pr-13362 (f90d48b) with 3.15 (2c4479f)²}

Footnotes

1. 86 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on 3.15 (d280ad5) during the generation of this report, so 2c4479f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩