Even if everything else works well, you should consider the limitation of maximum number of allowed TCP connection per second, imposed by your browser and/or OS.
By The way, are you sending ObjectMessage or TextMessage? I have faced a challenge to deserialize ObjectMessage and reported a bug at https://issues.jboss.org/browse/RF-11377
What did you think with "consider the limitation of maximum number of allowed TCP connection per second, imposed by your browser and/or OS"? I have now limited sending messages with delay (which is 500 ms) - that means maximum 2 per seconds are sent. And it looks like it works now (this behaviour (described above) didn't happen so far). I am sending TextMessage(s).
Thanks for your time.
If you get a chance, please try to check with some object message. You can use the sample I have updoaled with the bug report.