Hi Karthik,
Are you able to compare the WebView performance in 9.5.2 against earlier versions of WebView, that you notice a drop in performance ?
The presentation layer changed in 9.5 to use HTML5 compliant technology as opposed to relying on Silverlight in the past.
One thing we had seen is that dashboards can be slow to load where there are a lot of alerts on the screen.
This is because the default behaviour is to 'draw' all of the alerts in the background and then 'paint' them to the screen when they are all ready.
So that can be a reason for the timeout.
It would be interesting to know if you have issues on dashboards where there are little or no alerts posted.
We've not necessarily seen the same problems in the Investigator so it's not necessarily true that your cluster is perfectly fine, there could still be something that could be tweaked on that side, particularly as Guenter says if you might have large amount of historical data, or perhaps metric groupings and alerts in dashboards are evaluating a large amount of metrics.
Thanks,
David