I tried the suggested method, but ran into couple of issues.
I can only enable debug mode after I start the program (.. and after 30mins wait until the program becomes responsive). When enabled, it is either empty or contain 2 lines pasted in my earlier post. Obviously, when I start using the program, it fills up, but I don't have a problem with functionality at all, so I am not sure if it would be relevant?
When I try running the shortcut with -d parameter, the program simply won't start at all.
I tried uninstalling MusicBrainz Picard including deleting all plugins from my hdds and cleaning the registers. Fresh install surprisigly worked flawlessly first 2 times, then after that the unresponsive startup is back. All I did is go to options and changed the language (I also seemed to be logged in by default).