1. Call the telnet tool
telnet <host name> <telnet port 5NN08>
2. Login as j2ee_admin (dual stack) or Administrator (java stack)
3. List the cluster nodes
4. Jump to a server node
5. Go to deploy service
6. List all the applications that are currently starting
list_app | grep starting
Repeat step 6 until you can see that a particular application keeps showing up in starting status.
You now have the application that is taking time to start.
Take 3-4 java thread dumps (stack trace) with an interval of 30 secs using jcmon. Analysis of these thread dumps with special focus on the application that is in starting status can help you (or SAP support) identify the issue.
Finally, check the locking adapter to see if there are any hanging locks that may be causing the application to hang in that status.
Usually, when you have multiple server nodes, restarting one of the server nodes speeds up the startup of other server nodes.