Mem optimize #844

Job	Run time
clang-format	5m 37s
Docker	14m 11s
Linux (LLVM 14)	15m 55s
Coverage (STP)	37m 26s
Linux (LLVM 13)	17m 25s
macOS	11m 14s
Coverage (Z3)	47m 34s
Linux (LLVM 12)	16m 20s
Linux (LLVM 11, Doxygen)	15m 26s
Linux (LLVM 10)	17m 3s
Linux (LLVM 9)	15m 7s
Linux (ASan)	52m 1s
Linux (UBSan)	48m 33s
Linux (MSan)	1h 0m 43s
Linux (Z3 only)	19m 5s
Linux (metaSMT)	35m 37s
Linux (STP master)	15m 12s
Linux (Latest klee-uclibc)	19m 48s
Linux (Asserts disabled)	17m 16s
Linux (No TCMalloc, optimised runtime)	20m 9s
	8h 21m 42s

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