Node.js unveiled the new stable version of Node.js v0.8. In the changelog on the blog they provide few performance benchmarks, and compare Nodejs new version with the previous one! Here are performance graphs!
All these graphs were made using NodeJS blog data and the performance tests they made. AWESOME !
They made all these Node benchmarks on a OS X laptop using io.js
Node.js write performance
Node.js read performance
Node.js web performance
For more details have a look to the full NodeJS v0.8 note on node blog. Really a HUGE step!