I also configured the Neko parser along the RichFaces 3.3.3 and, we haven't got any performance improvement.
What I highly suggest you is:
1. Use the maven plugin to get the smaller JS & CSS RichFaces file: https://community.jboss.org/wiki/MavenResourceDependencyPluginReference
We really got better results after using customized JS.
Note:o analyze the performance.
1. We used PageSpeed & YSlow (firefox plugin).
2. For AJAX requests: <a4j:log>
The Ajax4JSF POLL component's performance which is refreshed with interval 1000 is very slow.
Usage of a4j:log - could be usefull to check client side processing. But in this concrete poll case I believe that such a long processing caused by not limited decoding/processing area and reRendering of huge parts of the pages. So there you should use phaseTracker to log server side processing.
About problems related to concrete components - yes if you for examples creting table with 100 rows and 10 columns and placing some kind of rich:someInput to every cell - it will not works smoothly as every input initiate client side objects and that could cause too much JS processing on the page.
Every case in general should be explored separatelly.. General suggestions I think is known to you all:
We have been facing the exact same problem in our JSF/Richfaces 3.3 application.
Finally we fixed it. Added a blog entry here
Please have a look. I hope it helps you or somone else struggling with this annoying performance issue.