To address performance issues with the Portal, the best approach for troubleshooting the problem is to perform the action and then directly look at the log files from the TDM Portal to see what has changed. In your file viewer, sort your log files from newest to oldest to see the files that have changed inside the log directory after you performed the action.
Afterwards, take a look at each of the files. If there is an issue, it will most likely show up towards the end of the file. In this case we found this entry...
2017-12-04 17:50:45.288 UTC [ERROR] [http-nio-8080-exec-3 ] --- [U:Administrator][M:GET][P:/api/ca/v1/checkpoints] c.c.t.v.c.VDataController: Cannot authenticate with appliance vtdm-appliance-b8d25f08 - I/O error on POST request for "https://vtdm-appliance-b8d25f08:8443/authenticate": Connection timed out: connect; nested exception is java.net.ConnectException: Connection timed out: connect
To address this problem, we unregistered the vTDM virtual appliance from the portal (since it was no longer active), and now the Self Service Catalog is now back to opening up in less than 5 seconds on the users machine.