Any ideas on why they use:

1. MessagePack (instead of, say, FlatBuffers – am I wrong to think that FlatBuffers are more efficient? (and the format was created by Google))

2. ELF binaries (instead of, say, taking a clean-sheet approach to executable formats)

Also, on ELF they say: "The loading position of the ELF is random and does not follow the v_addr specified in the ELF program header."

(They're talking about ASLR.) This just highlights for me that a more efficient format is possible, one that doesn't have a virtual address in its headers. Perhaps there are even bigger wins possible with a clean-sheet format.