There's the test source http://github.com/MadRabbit/taskspeed .
Okay, okay. Don't hold your breath. It's just in WebKit. In FF it's faster than Prototype at about 20% and still slightly faster than jQuery. In Opera it about same speed as jQuery and a little bit slower than Prototype. In IE... Well... Who uses that obsolete browser anyway?
PS: I would not believe tests result for jQuery on the benchmark, case when Prototype and RightJS were honestly loaded with elements building, updating etc. But as jQuery does not have this functionality, tests for it just feed the results with strings of already created html. Kinda cheating, you know.