Ofbiz Application Need to Restart

[ofbizprod]

We have created one web based ERP solution using Ofbiz. Problem is that we have to restart the application (apache-tomcat instance) every couple of hours otherwise website is not opening. There are no errors found in application as well as system log. Application is hosted on OpenSuse Linux on X-Series IBM box.
Created web based application in ofBiz and deployed the same. Application is running fine until few load of user (around 50 or more) started using the application. The application slow down and no one can use the same thereafter.

I have done another solutions for the same, I have deployed one more instances of the application and pointed to the same database, then my application can take the load of 80 user concurrently. But i need to understand what is the maximum user ofbiz can take concurrenlty. if ofbiz can take more than 1000 user what setting i need to do or what kind of deployment i need to take care.

following is the environment which i m using.

1. 9.0.10 PostGres DB on the different server (i m sure the post is running perfectly,as i have increaed the no of connection too)
2. Suse Linux OS
3. JAVA 1.6.x
4. JRE
5. OfBiz 9.0.x

Kindly suggest how to troubleshoot.