Mem optimize #797

Job	Run time
clang-format	5m 44s
Docker	10m 36s
Linux (LLVM 14)	15m 42s
Linux (LLVM 13)	14m 5s
Linux (LLVM 12)	15m 5s
Linux (LLVM 11, Doxygen)	13m 22s
Linux (LLVM 10)	13m 13s
Linux (LLVM 9)	12m 44s
Linux (ASan)	39m 5s
Linux (UBSan)	32m 28s
Linux (MSan)	46m 30s
Linux (Z3 only)	16m 26s
Linux (metaSMT)	31m 40s
Linux (STP master)	18m 21s
Linux (Latest klee-uclibc)	21m 3s
Linux (Asserts disabled)	16m 12s
Linux (No TCMalloc, optimised runtime)	17m 51s
Coverage (STP)	31m 10s
Coverage (Z3)	43m 29s
macOS	10m 22s
	7h 5m 8s

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