Intersection speedup and refactor #290

Job	Run time
warnings-base (ubuntu-latest)	1m 19s
run-tests (ubuntu-latest)	1m 15s
warnings-base (macos-latest)	1m 39s
run-tests (macos-latest)	57s
run-test-performance (ubuntu-latest)	1m 5s
run-test-performance-base (ubuntu-latest)	46s
warnings-new (ubuntu-latest)	51s
run-test-performance (macos-latest)	1m 37s
run-test-performance-base (macos-latest)	1m 39s
warnings-new (macos-latest)	1m 25s
code-coverage	0s
compare-performance	0s
compare-versions	0s
	12m 33s

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