The configuration is within the file tomcat/conf/server.xml .
The maximum number of request processing threads to be created by this Connector, which therefore determines the maximum number of simultaneous requests that can be handled. If not specified, this attribute is set to 200.
As reference, all available settings are in http://tomcat.apache.org/tomcat-5.5-doc/config/http.html .
Vontu by default has it set to 150.
<Connector URIEncoding="UTF-8" acceptCount="100" clientAuth="false" debug="0" disableUploadTimeout="true" enableLookups="false" keystoreFile="conf/.keystore" keystorePass="protect" maxSpareThreads="75" maxThreads="150" minSpareThreads="25" port="443" scheme="https" secure="true" sslProtocol="TLS"/>
In realistic scenarios the customer will have a restricted set of users that can access incidents and manage them.
Out of all these users, you rarely have them concurrently executing reports or interacting at the exact same time. So this in most cases is a reasonable value.
In real world you look usually at a scenario where an end-user clicks on a report and views the data for 10, 20 seconds. Then interacts again. So the numbers of users being served in parallel is much higher than the value of 150 would suggest.