Bring back the benchmarks

[tabo]

I just watched this fantastic presentation from @jrief, and in his very last comment he mentions that there are no benchmarks. Turns out we used to have great benchmarks comparing the 3 implementations and even MPTT. Since our API hasnt changed, we could just recover them from git.

[tabo]

See ea33ce7124769938c1cd683b99c8892ad58a111e