firefox 4 - comet iframe, pushes(javascript) are not executed correctly

I have an application t开发者_运维问答hat uses forever iframe(comet), this is working fine in firefox 3.6. But in firefox 4, pushes(javascript code that is sent from server) are not executed properly means firefox 4 is skipping some pushes, I have checked with firebug, there is no javascript error. I have tried, but unable to find the root of the problem?

I'm experiencing similar problems when using streamhub. This seems to be related to Firefox' speculative parsing.