If you can provide modern numbers, I'd appreciate it!

Maybe my information is out of date, but I just now picked a random benchmark (the fasta one from the language shootout) and ran it against v8-3.14.5.10 and luajit-2.0.3 (Fedora 21, latest available via yum), and luajit came out quite a bit ahead. I grant that it's a really naive benchmark setup and shouldn't be taken seriously, but my investment here is pretty minimal :)

    $ time luajit-2.0.3 fasta.lua 25000000 > /dev/null
    luajit-2.0.3 fasta.lua 25000000 > /dev/null  8.60s user 0.01s system 100% cpu 8.613 total

    $ time d8 --nodebugger fasta.js > /dev/null -- 25000000
    d8 --nodebugger fasta.js -- 25000000 > /dev/null  12.80s user 0.51s system 100% cpu 13.209 total

Edit: https://gist.github.com/spion/3049314 is another microbenchmark where Luajit quite handily outperforms not just v8, but equivalent C code!