My original solution, an interpreter implemented in C++:
aoc2018/21 % time ./p2.exe < input.txt
13943296
./p2.exe < input.txt 22.723 total
Recompiled to x86-64:
elfcode-x64-recompiler % time ./p2.exe < input.txt
13943296
./p2.exe < input.txt 0.828 total