Mem optimize #849

Job	Run time
clang-format	5m 32s
Coverage (STP)	38m 3s
Docker	11m 18s
Coverage (Z3)	43m 2s
macOS	11m 3s
Linux (LLVM 14)	15m 4s
Linux (LLVM 13)	19m 6s
Linux (LLVM 12)	14m 36s
Linux (LLVM 11, Doxygen)	15m 44s
Linux (LLVM 10)	14m 39s
Linux (LLVM 9)	21m 35s
Linux (ASan)	47m 52s
Linux (UBSan)	36m 54s
Linux (MSan)	48m 9s
Linux (Z3 only)	17m 32s
Linux (metaSMT)	40m 54s
Linux (STP master)	18m 4s
Linux (Latest klee-uclibc)	14m 48s
Linux (Asserts disabled)	15m 13s
Linux (No TCMalloc, optimised runtime)	20m 34s
	7h 49m 42s

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