I never expected it to come down to this, but the real culprit is ... Gosu::Font#draw!
The #draw calls take one second during start... That's ridiculous.
Okay, here's the deal:
All my font objects used the Gosu::default_font_name font. As you see above it's insanely slow.
Then I changed to "Droid Sans" and there it is... ~0.2 seconds. I *could* imagine that has something to do with
them, because
I installed them recently and they basically touch everything font related.
Well, now I have wasted a day for something stupid again. :P
Happy new year!