chore: optimize a few code paths

[SimonSchick]

Pull Request check-list

Please make sure to review and check all of these items:

• Does npm run test or npm run test-DIALECT pass with this change (including linting)?
• Does the description below contain a link to an existing issue (Closes #[issue]) or a description of the issue you are solving?
• Have you added new tests to prevent regressions?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Did you follow the commit message conventions explained in CONTRIBUTING.md?

Description of change

Basically #10553 but without the forEach changes.

[codecov]

Codecov Report

Merging #10570 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #10570      +/-   ##
==========================================
+ Coverage   96.18%   96.18%   +<.01%     
==========================================
  Files          92       92              
  Lines        9007     9009       +2     
==========================================
+ Hits         8663     8665       +2     
  Misses        344      344

Impacted Files	Coverage Δ
lib/dialects/postgres/connection-manager.js	94.61% <100%> (ø)	⬆️
lib/model.js	96.67% <100%> (ø)	⬆️
lib/utils.js	98.35% <100%> (+0.01%)	⬆️
lib/sequelize.js	96.27% <100%> (ø)	⬆️
lib/deferrable.js	71.42% <100%> (-1.91%)	⬇️

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