Ok thanks Wolfgang for investigating.
Yes the problem still occurs after carrying out the customizing of views as you described.
The JDBC trace is here: https://www.dropbox.com/s/x2f07a81k7vt43w/HDB_jdbctrace_01.log
That is a trace of opening the studio and immediately opening the Catalog folder (with urls etc removed). That is when it hung. I left it running 20 minutes and the trace file was not getting any bigger, so anything the system was going to log should be in there.