[chore] Optimized KBlock mem #873

Job	Run time
Docker	11m 53s
clang-format	6m 32s
Coverage (STP)	51m 37s
Linux (LLVM 14)	22m 35s
Coverage (Z3)	42m 43s
Linux (LLVM 13)	17m 17s
macOS	13m 8s
Linux (LLVM 12)	21m 52s
Linux (LLVM 11, Doxygen)	16m 25s
Linux (LLVM 10)	21m 51s
Linux (LLVM 9)	16m 7s
Linux (ASan)	48m 50s
Linux (UBSan)	1h 0m 32s
Linux (MSan)	55m 31s
Linux (Z3 only)	14m 55s
Linux (metaSMT)	36m 36s
Linux (STP master)	15m 18s
Linux (Latest klee-uclibc)	20m 50s
Linux (Asserts disabled)	23m 3s
Linux (No TCMalloc, optimised runtime)	14m 27s
	8h 52m 2s

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