These things take a long time. Heck, it might even be a bit early to call LLVM mature. Sure, it supports a C and C++ compiler, but I don't think it has anything production-ready for much else.
By comparison the Parrot project with the widest use is Rakudo, which is still just at a testing stage. Maybe there's some larger user of Parrot that I haven't heard about, so correct me if I'm wrong.
The URL to the benchmark script was broken so I couldn't run it.
Don't get me wrong, I think Parrot's very neat. But I could see why compiler implementors would be sceptical of it since it's not feature complete, and seemingly not very optimized. So there's a lot of unknowns.
One Bytecode to rule them all, One Bytecode to find them, One Bytecodeto bring them all and in the darkness bind them
:-)