Core2Duo 2.67 Ghz here, seems to take a few secondes (probably 4 or 5), but if it won't take more time with more roms, it seems okay (I tried with 2 roms and so, the concern was to know if the load time is exponential).
Well, slow is maybe not the best word, but it's not as fast as the emus which just load the roms content.
And I don't think what I talk about is because of the favorite/clone/genre/categories and such as I don't use any (for now) on any emus (if it was the case, it would be the same speed for the other emus, no?).
It was just a proposition anyway so that's not a problem, but the proposition wasn't to remove the database support, rather to be able to save the database to a file, to avoid reading everything at each startup, when you always use the same set of roms.