It can handle it just fine.* You will need to be very patient indeed, however, as Arkngt more or less said. If it appears not to be doing anything for a while, that's because it's still "thinking". And it will do so for ages...
That's just the way it is with large mods and the OMOD format / process.
* In fact, it can handle even bigger mods, like the original QTP3, and others.
This is indeed strange since I got an error message. Altough, if you say so maybe I did something I shouldn't have and that caused the problem. I will give it another try (while I'm educating myself about how to use wrye bash.
For what concern the second suggestion, looking at the size and the description of the linked addon, that seems to me the reduced package only. I'm saving that as a last resort (also because I would prefer to avoid downloading another 1.7GB file for today).
Thanks again to everyone.