Any numbers for node on ARM? I was told that recently v8 releases have had significant performance regressions for ARM devices by a JS dev at a meetup.
If you know that JS dev personally please ask him to file the bug (http://code.google.com/p/v8/issues/entry) or send any information he has about regressions to v8-users mailing list.
I don't think there were any bugs opened recently about perf regressions on ARM devices.