perf: Improve nb cells #572

Job	Run time
cppcheck	1m 44s
pre-commit	2m 38s
macos-mamba	3m 21s
linux-mpi-mamba	1m 11s
linux-mamba (gcc-10, gcc, gcc-10 g++-10, gcc-10, g++-10)	1m 47s
linux-mamba (gcc-11, gcc, gcc-11 g++-11, gcc-11, g++-11)	1m 46s
linux-mamba (gcc-12, gcc, gcc-12 g++-12, gcc-12, g++-12)	1m 47s
linux-mamba (clang-11, clang, clang-11, clang-11, clang++-11)	1m 48s
linux-mamba (clang-12, clang, clang-12, clang-12, clang++-12)	1m 48s
linux-mamba (clang-13, clang, clang-13, clang-13, clang++-13)	1m 48s
linux-mamba (clang-14, clang, clang-14, clang-14, clang++-14)	1m 31s
linux-mamba (clang-15, clang, clang-15, clang-15, clang++-15)	1m 48s
	22m 57s

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