diff --git a/src/optimize-subcity.rs b/src/optimize-subcity.rs
index c45509b..926f061 100644
--- a/src/optimize-subcity.rs
+++ b/src/optimize-subcity.rs
@@ -25,10 +25,32 @@ fn main() {
         .next().expect("No best layout found");
     eprintln!("Found best layout, ID {}, price {}", best_layout.id(), get_price(&city, best_layout.houses()));
 
-    let x_range = 5533..=12000;
-    let y_range = 4750..=12500;
-    //let x_range = 5533..=8000;
-    //let y_range = 4750..=8000;
+    //let x_range = 5533..=12000;
+    //let y_range = 4750..=12500;
+    //let x_range = 9500..=14100;
+    //let y_range = 10300..=14400;
+    //let x_range = 14900..=16200;
+    //let y_range = 7720..=10400;
+    //let x_range = 9982..=16383;
+    //let y_range = 0..=2720;
+    //let x_range = 7720..=12000;
+    //let y_range = 5608..=11000;
+    //let x_range = 3542..=8423;
+    //let y_range = 4832..=8423;
+    //let x_range = 1200..=9200;
+    //let y_range = 9000..=16383;
+    //let x_range = 9200..=16383;
+    //let y_range = 9200..=16383;
+    //let x_range = 9201..=16383;
+    //let y_range = 0..=7500;
+    //let x_range = 11100..=13333;
+    //let y_range = 14700..=16383;
+    //let x_range = 0..=7500;
+    //let y_range = 0..=7500;
+    let x_range = 0..=7500;
+    let y_range = 9500..=16383;
+    //let x_range = 9500..=16383;
+    //let y_range = 0..=7500;
     eprintln!("X {}-{}, Y {}-{}", x_range.start(), x_range.end(), y_range.start(), y_range.end());
 
     let static_houses: Vec<House> = best_layout.houses().iter()
@@ -56,11 +78,21 @@ fn main() {
 
     //let mut subcity_db = MemoryLayoutDB::new();
     let filename = format!("X{}_{}Y{}_{}ID{}.sqlite", x_range.start(), x_range.end(), y_range.start(), y_range.end(), best_layout.id());
-    let mut subcity_db = SqliteLayoutDB::from_file(&filename).unwrap();
+    let mut subcity_db = SqliteLayoutDB::from_file(&filename, true).unwrap();
+
+    // The following part merges best subcity layouts back into the global layout and
+    // inserting them into the database
+
+    // Setting this value allows attempts at improving suboptimal subcities after merging them back.
+    // A subcity may result in a better score than original even if the subcity is worse than the
+    // original if global improvements improve the cost.
+    //const SUBOPTIMAL_SUBCITY_COST_MARGIN: u32 = 5000;
+    //const CHECKED_CITY_LIMIT: usize = 50;
 
     //for layout in subcity_db.layouts().iter()
-    //    .filter(|x| get_price(subcity.city(), x.houses()) < removed_price)
-    //    .sorted_by(|x, y| get_price(subcity.city(), x.houses()).cmp(&get_price(subcity.city(), y.houses()))) {
+    //    .filter(|x| get_price(subcity.city(), x.houses()) < removed_price + SUBOPTIMAL_SUBCITY_COST_MARGIN)
+    //    .sorted_by(|x, y| get_price(subcity.city(), x.houses()).cmp(&get_price(subcity.city(), y.houses())))
+    //    .take(CHECKED_CITY_LIMIT) {
     //    let price = get_price(subcity.city(), layout.houses());
     //    let mut full_houses = subcity.to_full_houses(layout.houses());
     //    assert!(city::is_valid(&city, &full_houses).is_some());
@@ -71,7 +103,7 @@ fn main() {
     //    }
     //    let seed: u64 = thread_rng().gen();
     //    let mut rng = StdRng::seed_from_u64(seed);
-    //    optimization::iterate_improvements(&mut house_layout, &mut rng, true);
+    //    optimization::iterate_improvements(&mut house_layout, &mut rng, true, false);
     //    eprintln!("Improvements finished");
     //    assert!(house_layout.is_valid());
     //    let improved_price = city::get_price(&city, house_layout.houses());
@@ -82,9 +114,17 @@ fn main() {
 
     //    assert!(city::is_valid(&city, &full_houses).is_some());
     //    println!("Layout {}, price {}, full price {}", layout.id(), price, city::get_price(&city, &full_houses));
-    //    // Be careful with duplicates here
-    //    //sqlite_db.add_layout(&full_houses, true);
-    //    //println!("Inserted into the global DB");
+    //    if improved_price < city::get_price(&city, best_layout.houses()) {
+    //        eprintln!("Found a new best layout for the full city");
+    //        println!("Found a new best layout for the full city");
+    //        println!("Layout {}, price {}, full price {}", layout.id(), price, city::get_price(&city, &full_houses));
+    //    }
+    //        //eprintln!("NOT inserting into the DB");
+    //        // Be careful with duplicates here
+    //        sqlite_db.add_layout(&full_houses, true);
+    //        eprintln!("Inserted into the global DB");
+    //        println!("Inserted into the global DB");
+    //    //}
     //}
     //return;
 
@@ -96,12 +136,16 @@ fn main() {
     //   Generate `WEIGHTED_RANDOM_LAYOUTS` layouts weighted by scores from existing layouts
     // }
 
-    const FULL_RANDOM_LAYOUTS: usize = 100;
-    const DB_CHOICE_PROBABILITY: f64 = 0.90;
-    const WEIGHTED_RANDOM_LAYOUTS: usize = 200;
+    const FULL_RANDOM_LAYOUTS: usize = 200;
+    const DB_CHOICE_PROBABILITY: f64 = 0.95;
+    const WEIGHTED_RANDOM_LAYOUTS: usize = 100;
     const CUT_COMBINE_TOP_LAYOUTS: usize = 500;
     const IGNORED_WEIGHT_RATIO: f64 = 0.5;
 
+    const THREAD_COUNT: usize = 12;
+
+    rayon::ThreadPoolBuilder::new().num_threads(THREAD_COUNT).build_global();
+
     if subcity_db.layouts().len() == 0 {
         let mut full_random_layouts = Vec::new();
 
@@ -119,7 +163,7 @@ fn main() {
         }));
 
         for houses in &full_random_layouts {
-            subcity_db.add_layout(houses, true);
+            subcity_db.add_layout(houses, true).expect("Failed to add new layout");
         }
 
         eprintln!("Finished initial full random population");
@@ -127,9 +171,13 @@ fn main() {
         eprintln!("Skipping initial full random population because DB is non-empty [{} layouts]", subcity_db.layouts().len());
     }
 
-    let best_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).min().unwrap();
-    let worst_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).max().unwrap();
-    eprintln!("Best {}, worst {} [{} layouts]", best_price, worst_price, subcity_db.layouts().len());
+    fn print_status<TDB: LayoutDB>(db: &TDB, subcity: &City) {
+        let best_price: u32 = db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.get_price(*h) as u32).sum()).min().unwrap();
+        let worst_price: u32 = db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.get_price(*h) as u32).sum()).max().unwrap();
+        eprintln!("Best {}, worst {} [{} layouts]", best_price, worst_price, db.layouts().len());
+    }
+
+    print_status(&subcity_db, subcity.city());
 
     let mut cache = combine::CompatibilityCache::new();
 
@@ -138,10 +186,8 @@ fn main() {
         // This is a bottleneck when it comes to multithreading, it only runs on a single thread
         combine::iterate_combines(&mut subcity_db, CUT_COMBINE_TOP_LAYOUTS, subcity.city(), &mut cache, false);
 
-        let best_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).min().unwrap();
-        let worst_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).max().unwrap();
         eprintln!("Finished cut combines");
-        eprintln!("Best {}, worst {} [{} layouts]", best_price, worst_price, subcity_db.layouts().len());
+        print_status(&subcity_db, subcity.city());
 
         let mut weighted_random_layouts = Vec::new();
         // Only using the underlying memory-based DB is required here as the SqliteLayoutDB
@@ -152,25 +198,25 @@ fn main() {
             let mut rng = StdRng::seed_from_u64(seed);
             let mut layout = HouseLayout::new(subcity.city());
 
+            let best_price: u32 = memory_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).min().unwrap();
+            let worst_price: u32 = memory_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).max().unwrap();
             let price_range = worst_price - best_price;
             let max_price = best_price as f64 + (price_range as f64 * (1. - IGNORED_WEIGHT_RATIO));
             //eprintln!("Starting random weighted population {}, using DB, score range {}-{}, DB use probability {}...", i, best_price, worst_price, DB_CHOICE_PROBABILITY);
             population::populate_using_db(&mut layout, &mut rng, memory_db, best_price as f64, max_price as f64, DB_CHOICE_PROBABILITY);
             //eprintln!("Finished random init {}, price: {}, houses: {}", i, layout.price(), layout.houses().len());
-            optimization::iterate_improvements(&mut layout, &mut rng, false);
+            optimization::iterate_improvements(&mut layout, &mut rng, false, false);
             //eprintln!("Finished iterated improvements {}, price: {}, houses: {}", i, layout.price(), layout.houses().len());
             layout.houses().clone()
         }));
 
         for houses in &weighted_random_layouts {
-            subcity_db.add_layout(houses, true);
+            subcity_db.add_layout(houses, true).expect("Failed to add new layout");
         }
 
         let w_best: u32 = weighted_random_layouts.iter().map(|houses| houses.iter().map(|h| subcity.city().get_price(*h) as u32).sum()).min().unwrap();
         let w_worst: u32 = weighted_random_layouts.iter().map(|houses| houses.iter().map(|h| subcity.city().get_price(*h) as u32).sum()).max().unwrap();
-        let best_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).min().unwrap();
-        let worst_price: u32 = subcity_db.layouts().iter().map(|layout| layout.houses().iter().map(|h| subcity.city().get_price(*h) as u32).sum()).max().unwrap();
         eprintln!("Finished weighted random population, price range {}-{}", w_best, w_worst);
-        eprintln!("Best {}, worst {} [{} layouts]", best_price, worst_price, subcity_db.layouts().len());
+        print_status(&subcity_db, subcity.city());
     }
 }