Hi,
The web Intelligence Processing server has a setting for Maximum Connections which defaults to 50. You can extend as per your requirements. The question you need to ask yourself is how many concurrent Webi request will the server receive, then you can configure it accordingly.
I would recommend that you do a proper sizing exercise to ensure that you have sufficient resources/servers available.
For your Tomcat taking 30% CPU, that's not normal. Have a look at the log files for Tomcat and see if anything is happening there. If you have a lot of Dashboards processing (opening) it will require Tomcat to do some extra processing so that can be normal, but if you aren't doing anything it should calm down. Remember that if you have a big dashboard with lots of connections it will require quite a bit of resources on Tomcat/BO and also client to process.
Regards,
Josh