Free list properly #228

Job	Run time
build (ubuntu-latest, Debug, gcc, 0)	10s
build (ubuntu-latest, Debug, gcc, 2)	48s
build (ubuntu-latest, Debug, clang, 0)	16s
build (ubuntu-latest, Debug, clang, 2)	53s
build (ubuntu-latest, Release, gcc, 0)	31s
build (ubuntu-latest, Release, gcc, 2)	22s
build (ubuntu-latest, Release, clang, 0)	16s
build (ubuntu-latest, Release, clang, 2)	31s
build (macos-latest, Debug, gcc, 0)	16s
build (macos-latest, Debug, gcc, 2)	49s
build (macos-latest, Debug, clang, 0)	12s
build (macos-latest, Debug, clang, 2)	44s
build (macos-latest, Release, gcc, 0)	14s
build (macos-latest, Release, gcc, 2)	21s
build (macos-latest, Release, clang, 0)	17s
build (macos-latest, Release, clang, 2)	21s
build (windows-latest, Debug, cl, 0)	4m 45s
build (windows-latest, Debug, cl, 2)	4m 50s
build (windows-latest, Release, cl, 0)	1m 28s
build (windows-latest, Release, cl, 2)	46s
	18m 50s

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