perf: avoid creating unnecessary large or temp arrays

[jbedard]

https://github.com/aspect-build/rules_swc/commit/6bf6610494cbb7589b5e34f3d834abd8c19e55d0 made a noticeable difference so I think we should do similar elsewhere, especially when iterating over potentially large arrays.

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Type of change

• Performance (a code change that improves performance)

Test plan

• Covered by existing test cases