onmousemove event ajax requset frequency

[zhen_jane]

I have this onmousemove event handler and that triggers the following ajax request to be sent to the server to update a bean variable:

<a4j:form>
<a4j:jsFunction name="updateTabIndex" eventsQueue="tabonmouseout" ignoreDupResponses="true" requestDelay="400">
<a4j:actionparam name="param1" assignTo="#{sessionBean.selectedIndex}" />
</a4j:jsFunction>
</a4j:form>

I used eventsQueue, ignoreDupResponse and requestDelay trying to control the frequency of the ajax requests sent by client. Still sometimes, I see wierd slow loading of page in browser. From my understanding, I'm putting the ajax requests to a separate event queue, and the event is sent every 400ms if the event is different from the previous one (?), and the duplicate response will be ignored. Am I right? How do I improve this frequency control?

thanks
jane