Just judging by the pictures your build is seriously lacking optimization. A few points...
For paths/roads, if you want a detail texture I suggest you put together (or find a download for) some large print bricks. Filling every path with randomly shaded, grey, flat, circles not only looks awful, but is incredibly wasteful. A large plate print brick (perhaps 8x10 or 8x16) with a decent texture could work wonders.
Additionally, any details not visible to the player (eg. the outside of the palisades, some of the roofs, etc) should be removed. It's just a waste of bricks and basically implies laziness. A better method for the castle walls would be to use the large 8x8 cube bricks. That way, players aren't going to be distracted by some wasteful wall that should be a background feature. You can still keep some detail on the tops of the wall and perhaps even frame the 8x8s with some simple arches, but just keep it simple.
In fact, that awful "stairway to heaven" thing you have in the center of the map just makes your problems worse; not only does it's height reveal how small the playable area is, it also forces you to add unnecessary detail to the tops of buildings. Even if one ignores the fact that the stairway is a massive eyesore, there is still the issue of how out-of-place it looks in a fantasy/medieval setting; structures simply were not built that way and especially not out of stone.
I appreciate that your massive brown walls are an attempt to divide the game world and reduce "lag", but in all honestly it looks terrible and is yet another huge waste of bricks. A better method would be to use the terrain block (this means whipping out those mapping skills) to divide the areas. Not only will it look more natural and save you thousands of bricks, it will also save you time and help with planning if you decide to use pre-made heightmaps for terrain generation.
Another issue is how incredibly repetitive the build is overall. The birds-eye-view is prime evidence of this. The duplicator wand is an amazing tool, but it is no supplement for building unique structures. Unless you are planning on running some kind of concentration camp, I'd use more variety. I realize some of that maybe the player housing you mentioned earlier and to this I'd say "abandon the idea". There is no reason to provide accommodation for players. If the best entertainment you can provide is giving them a cottage then you are in the wrong business.
I'd suggest a restart.
Poll