Mem optimize #848

Job	Run time
clang-format	1m 11s
Docker	1m 10s
Coverage (STP)	1m 10s
Linux (LLVM 14)	1m 9s
Coverage (Z3)	1m 14s
macOS	1s
Linux (LLVM 13)	1m 10s
Linux (LLVM 12)	1m 10s
Linux (LLVM 11, Doxygen)	1m 13s
Linux (LLVM 10)	1m 11s
Linux (LLVM 9)	1m 11s
Linux (ASan)	1m 10s
Linux (UBSan)	1s
Linux (MSan)	11s
Linux (Z3 only)	1s
Linux (metaSMT)	1m 11s
Linux (STP master)	1s
Linux (Latest klee-uclibc)	1m 12s
Linux (Asserts disabled)	1m 12s
Linux (No TCMalloc, optimised runtime)	22s
	17m 11s

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