There are couple of ways
1. Narrow down the slow pages to see which are actually slow by Running the Tomcat Analyze Job and see the top 20 slow actions portlet under log analysis
2. When you navigate to certain pages in new ux, use the browser console to see the pages which are slow and how much slow
3. You can enable SQL trace to see how long query took time to execute at database
4. If you are using Oracle as database, then you can query on the v$SESSION table and as soon as you hit the page you will see a row getting added and you will see SQLID you can run a explain plan on that query to see where its slow and how slow
There are multiple ways to tackle performance issues and it could be App layer, Database layer or network layer and we need to take respective actions and take it from there. Also performance tuning is iterative exercise and there is no single point solution unfortunately
Regards
Suman Pramanik