Small speed up to starting client requests

[bdraco]

What do these changes do?

Avoid some checks for uncommon cases

Avoid lower()ing default values that are rarely set.

Are there changes in behavior for the user?

no

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

no

[bdraco]

master can handle 13% more RPS than 3.9.5 and the performance is a bit more consistent until gc happens

There is still a lot of time spent in all the update_* functions that we likely can't do much better in:

aiohttp/aiohttp/client_reqrep.py

Line 258 in d684195

self.update_version(version)

There are so many options that its always going to be difficult to optimize them without making more invasive changes which probably aren't worth it.

master

3.9.5

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.56%. Comparing base (d684195) to head (0d30abc).
Report is 715 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9386   +/-   ##
=======================================
  Coverage   98.56%   98.56%           
=======================================
  Files         107      107           
  Lines       34995    34995           
  Branches     4146     4146           
=======================================
  Hits        34492    34492           
  Misses        335      335           
  Partials      168      168           

Flag	Coverage Δ
CI-GHA	98.44% <100.00%> (ø)
OS-Linux	98.10% <100.00%> (ø)
OS-Windows	96.52% <100.00%> (ø)
OS-macOS	97.79% <100.00%> (-0.01%)	⬇️
Py-3.10.11	97.66% <100.00%> (ø)
Py-3.10.15	97.65% <100.00%> (+0.04%)	⬆️
Py-3.11.10	97.67% <100.00%> (ø)
Py-3.11.9	97.73% <100.00%> (ø)
Py-3.12.6	98.15% <100.00%> (-0.01%)	⬇️
Py-3.13.0-rc.2	98.14% <100.00%> (ø)
Py-3.9.13	97.56% <100.00%> (ø)
Py-3.9.20	97.50% <100.00%> (ø)
Py-pypy7.3.16	97.12% <100.00%> (ø)
VM-macos	97.79% <100.00%> (-0.01%)	⬇️
VM-ubuntu	98.10% <100.00%> (ø)
VM-windows	96.52% <100.00%> (ø)

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[patchback]

Backport to 3.10: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.10/803d818d1eb2c5fdd9fce4c427d3062b6d39fd6b/pr-9386

Backported as #9388

🤖 @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/3.11/803d818d1eb2c5fdd9fce4c427d3062b6d39fd6b/pr-9386

Backported as #9389

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