I tried it on Chrome Version 34.0.1847.131 m (the latest). using the pystone benchmark:
In cPython 3.4.0b1 I got:
And in Firefox 29.0 I got:
These were the latest versions at the time of writing (I think) and taking the fastest of their four runs on the same machine gives:
|Platform||Best of 4 Pystone||Multiplier|
See the original article for caveats on the state of PyPy.js - it may only run pystone for all I know.
Of course it doesn't say much about Python speed but it may say something about Chrome vs Firefox speed? Who knows - lies, damned lies, and statistics!