This is an interesting thread, primarily because I don't see the point.
If we developers knew of some way to make calibre start faster (not put up spinners, but really start faster), we would do it. We aren't keeping a silver bullet in our pocket. After all, we would benefit more than you would. In the more than 150 person/days of development effort I have put on calibre this year, I have probably started calibre more than 5,000 times. Gee whiz, I wish I would have used that silver bullet.
For each person, the balance of using calibre is positive or it isn't. There are a lot of factors in that decision. Negatives: some people can't handle calibre's file system. Others can't handle the icons. Others can't handle the putative 'techie' bias of the application. Others don't like the gui. Others don't like the command line. And some don't like anything very much. (But we can be tranquil and thankful and proud, for man's been endowed with a ...
) And, of course, some can't handle its performance.
I won't bother with the positives. Most of you wouldn't be here if there weren't some for you.
Finally, calibre is free. You can try it for free. You can use it for free. You can stop using it for free. You can criticize it for free. You can even fix it for free. Each person makes a choice about which freedom to invoke. Of course, some choices are easier to make than others.
And yes, this post is also pointless.
