Hello.
I may be late in the thread, but I come back to the question of the splash screen. I found out where to set it, and it definitely comes AFTER the freeze.

I may try the 'safe mode' test, if ever I found out how to !

I may add that the 'Windows task manager' (if that its name) also completely freeze for a good minute at first Calibre start.

I may be wrong, but this is not a normal situation. I worked in assembly langage on a system 'real time' managing up to 48 terminals. There was a specific rule to obey when 'freezing' the system. You had to do it for some MILLISECONDS from time to time, to access data that could be changed by another process while you wanted to change it. If both were allowed, result could be catastrophic. So you 'lock' what was called 'interupt', set a flag saying 'this stuf is totaly reserved by me', and unlock the stuff. Then you do it back when finished, else everything will also die.

The same thing must exist in Win, to change things in a directory, or to manage multiple core running.

Anyway no other program I use do that freezing for more than 2 to 5 seconds.