[otrs] Version 6 very slow

We are finding version 6 very slow to use in comparison to v5, we are using the same hardware although I have added extra RAM and have moved /opt/otrs/var/tmp to a RAM disk to try to speed things up. We have a PostgreSQL back-end but that doesn’t seem to be under any duress. It appears that each time one moves to a different part of the application there is a significant pause. Returning to the same part is then faster a 2nd time. Any performance suggestions gratefully received. Glen.