Damn! I lost my time… Bad luck for you, I will say all the bad things I wanted to say any way.
First, your meshes are a mess. The normals are wrong half of the time. Switch all your objects to “Single Sided” at the bottom of the “Object Data” tab (The blue triangle.) and you’ll see. Horrors!
And that snow is super heavy. :eek: That’s insane. A less dense mesh with a bump map would give the same result. I removed a big shunk but it’s still crazy. Objects encased in glass are already bad for Cycles… If you add a super heavy mesh on top of that, no wonder it takes ages to render.
Then, there isn’t enough light in your scene. I tuned that and few more everywhere. (I’ll keep for myself what I wanted to say about the path lights. Any way, I’m the first to recognize I know nothing about it… and you found your mistake by yourself.)
Any way… With 200 samples, I got this:
I fixed all the normals and the fairy lights. (Subsurf goes after the array, never before.) I faked the glass. I added a big light. I used a little trick for the bottom part of the snow so that it doesn’t make a mess with glass bubble. (That’s the big chunk I removed.) I tuned a bit the little lights. I found what you did a bit weird.
See for yourself: (Well… Not yet… I forgot how big your file is. BA won’t accept it.)
To be continued…
EDIT: The blend file is here: http://www.pasteall.org/blend/24433
Be prepared for a long night of rendering.