A benchmark of bananabread in the shell is available as follows: 1. git clone git@github.com:kripken/misc-js-benchmarks.git 2. cd banana/shell 3. edit runme.sh so js points to your spidermonkey shell 4. run ./runme.sh Running it with --no-ion I get 8.74ms, while running it normally with IonMonkey I get 9.61ms per frame, almost 10% slower. (With --ion-limit-script-size=off, it is a few percent faster than normal ion. But there are noticeable large pauses and the variance goes up.)