clean up and notes #1546

Job	Run time
macos-latest: clang++ Release Threads	3m 5s
macos-latest: clang++ Release OneTBB	3m 20s
macos-latest: clang++ Release PaRSEC	3m 30s
ubuntu-20.04: /usr/bin/g++-9 Release Threads	1m 40s
ubuntu-20.04: /usr/bin/g++-9 Release OneTBB	3m 11s
ubuntu-20.04: /usr/bin/g++-9 Release PaRSEC	3m 14s
macos-latest: clang++ Debug Threads	2m 31s
macos-latest: clang++ Debug OneTBB	4m 20s
macos-latest: clang++ Debug PaRSEC	3m 52s
ubuntu-20.04: /usr/bin/g++-9 Debug Threads	2m 40s
ubuntu-20.04: /usr/bin/g++-9 Debug OneTBB	2m 35s
ubuntu-20.04: /usr/bin/g++-9 Debug PaRSEC	2m 48s
	36m 46s

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