I have noticed that it is quite a hassle to view clob data by double clicking onto it, since when the size of that specific row is more than 10+mb, then toad basically hangs, sometimes I wait for 5-10 minutes and then it finally loads that data. But very often, it does not happen at all.
Viewing Session Browser from another toad program, shows actually that the session is inactive and does not do any work - hence seems like hanged.
I have tried viewing it from Schema Browser and also via Editor, by writing select query.
On the contrast, when clicking onto "Export dataset" - and using this to extract Clob rows - this is works quite well, even 20-30+MB Clob data can be extracted within seconds.
This has been problem to me for a quite long time, so definetly not a problem for the past few releases.