diff --git a/egregoria/src/init.rs b/egregoria/src/init.rs
index 8ff7a49c..281d8e23 100644
--- a/egregoria/src/init.rs
+++ b/egregoria/src/init.rs
@@ -22,7 +22,7 @@ use crate::{
     ParCommandBuffer, RandProvider, Replay, RunnableSystem, RNG_SEED, SECONDS_PER_DAY,
     SECONDS_PER_HOUR,
 };
-use common::saveload::Encoder;
+use common::saveload::{Bincode, Encoder};
 use serde::de::DeserializeOwned;
 use serde::Serialize;
 
@@ -52,25 +52,25 @@ pub fn init() {
     register_resource_noserialize::<ParCommandBuffer<WagonEnt>>();
     register_resource_noserialize::<ParCommandBuffer<FreightStationEnt>>();
     register_resource_noserialize::<ParCommandBuffer<CompanyEnt>>();
-    register_resource_noinit::<Market>("market");
-    register_resource_noinit::<EcoStats>("ecostats");
-    register_resource_noinit::<EgregoriaOptions>("egregoriaoptions");
+    register_resource_noinit::<Market, Bincode>("market");
+    register_resource_noinit::<EcoStats, Bincode>("ecostats");
+    register_resource_noinit::<EgregoriaOptions, Bincode>("egregoriaoptions");
 
     register_init(init_market);
 
-    register_resource("tick", Tick::default);
-    register_resource("map", Map::default);
-    register_resource("train_reservations", TrainReservations::default);
-    register_resource("government", Government::default);
-    register_resource("pmanagement", ParkingManagement::default);
-    register_resource("binfos", BuildingInfos::default);
-    register_resource("game_time", || {
+    register_resource_default::<Tick, Bincode>("tick");
+    register_resource_default::<Map, Bincode>("map");
+    register_resource_default::<TrainReservations, Bincode>("train_reservations");
+    register_resource_default::<Government, Bincode>("government");
+    register_resource_default::<ParkingManagement, Bincode>("pmanagement");
+    register_resource_default::<BuildingInfos, Bincode>("binfos");
+    register_resource::<GameTime, Bincode>("game_time", || {
         GameTime::new(0.0, SECONDS_PER_DAY as f64 + 10.0 * SECONDS_PER_HOUR as f64)
     });
-    register_resource("coworld", || CollisionWorld::new(100));
-    register_resource("randprovider", || RandProvider::new(RNG_SEED));
-    register_resource("dispatcher", Dispatcher::default);
-    register_resource("replay", Replay::default);
+    register_resource::<CollisionWorld, Bincode>("coworld", || CollisionWorld::new(100));
+    register_resource::<RandProvider, Bincode>("randprovider", || RandProvider::new(RNG_SEED));
+    register_resource_default::<Dispatcher, Bincode>("dispatcher");
+    register_resource_default::<Replay, Bincode>("replay");
 }
 
 pub struct InitFunc {
@@ -128,7 +128,16 @@ fn register_resource_noserialize<T: 'static + Default + Send + Sync>() {
     }
 }
 
-fn register_resource<T: 'static + Send + Sync + Serialize + DeserializeOwned>(
+fn register_resource_default<
+    T: 'static + Send + Sync + Serialize + DeserializeOwned + Default,
+    E: Encoder,
+>(
+    name: &'static str,
+) {
+    register_resource::<T, E>(name, T::default);
+}
+
+fn register_resource<T: 'static + Send + Sync + Serialize + DeserializeOwned, E: Encoder>(
     name: &'static str,
     initializer: impl Fn() -> T + 'static,
 ) {
@@ -136,21 +145,19 @@ fn register_resource<T: 'static + Send + Sync + Serialize + DeserializeOwned>(
         INIT_FUNCS.push(InitFunc {
             f: Box::new(move |uiw| uiw.insert(initializer())),
         });
-        register_resource_noinit::<T>(name);
+        register_resource_noinit::<T, E>(name);
     }
 }
 
-fn register_resource_noinit<T: 'static + Send + Sync + Serialize + DeserializeOwned>(
+fn register_resource_noinit<T: 'static + Send + Sync + Serialize + DeserializeOwned, E: Encoder>(
     name: &'static str,
 ) {
     unsafe {
         SAVELOAD_FUNCS.push(SaveLoadFunc {
             name,
-            save: Box::new(move |uiworld| {
-                <common::saveload::Bincode as Encoder>::encode(&*uiworld.read::<T>()).unwrap()
-            }),
+            save: Box::new(move |uiworld| E::encode(&*uiworld.read::<T>()).unwrap()),
             load: Box::new(move |uiworld, data| {
-                if let Ok(res) = <common::saveload::Bincode as Encoder>::decode::<T>(&data) {
+                if let Ok(res) = E::decode::<T>(&data) {
                     uiworld.insert(res);
                 }
             }),
diff --git a/egregoria/src/lib.rs b/egregoria/src/lib.rs
index 7c35f53c..cb14e033 100644
--- a/egregoria/src/lib.rs
+++ b/egregoria/src/lib.rs
@@ -198,25 +198,27 @@ impl Egregoria {
         &mut self.world
     }
 
-    pub fn assert_equal(&self, other: &Self) {
-        assert_eq!(
-            self.resources.iter().count(),
-            other.resources.iter().count()
-        );
-
-        let serhashes = self.hashes();
-        let deserhashes = other.hashes();
-
-        for (key, hash) in deserhashes.iter() {
-            assert_eq!(serhashes.get(key), Some(hash), "key: {:?}", key,);
+    pub fn is_equal(&self, other: &Self) -> bool {
+        if self.resources.iter().count() != other.resources.iter().count() {
+            return false;
         }
 
-        for (key, hash) in serhashes.iter() {
-            if deserhashes.get(key).is_some() {
-                continue;
+        unsafe {
+            for l in &SAVELOAD_FUNCS {
+                let a = (l.save)(self);
+                let b = (l.save)(other);
+
+                if a != b {
+                    std::fs::write(format!("{}_a.json", l.name), &*String::from_utf8_lossy(&a))
+                        .unwrap();
+                    std::fs::write(format!("{}_b.json", l.name), &*String::from_utf8_lossy(&b))
+                        .unwrap();
+                    return false;
+                }
             }
-            assert_eq!(deserhashes.get(key), Some(hash), "key: {:?}", key,);
         }
+
+        true
     }
 
     #[profiling::function]
diff --git a/egregoria/src/map/map.rs b/egregoria/src/map/map.rs
index cd02c6f6..37ab2211 100644
--- a/egregoria/src/map/map.rs
+++ b/egregoria/src/map/map.rs
@@ -8,15 +8,15 @@ use geom::OBB;
 use geom::{Spline3, Vec2, Vec3};
 use ordered_float::OrderedFloat;
 use serde::{Deserialize, Serialize};
-use slotmapd::DenseSlotMap;
+use slotmapd::HopSlotMap;
 use std::collections::BTreeMap;
 use std::num::Wrapping;
 
-pub type Roads = DenseSlotMap<RoadID, Road>;
-pub type Lanes = DenseSlotMap<LaneID, Lane>;
-pub type Intersections = DenseSlotMap<IntersectionID, Intersection>;
-pub type Buildings = DenseSlotMap<BuildingID, Building>;
-pub type Lots = DenseSlotMap<LotID, Lot>;
+pub type Roads = HopSlotMap<RoadID, Road>;
+pub type Lanes = HopSlotMap<LaneID, Lane>;
+pub type Intersections = HopSlotMap<IntersectionID, Intersection>;
+pub type Buildings = HopSlotMap<BuildingID, Building>;
+pub type Lots = HopSlotMap<LotID, Lot>;
 
 #[derive(Copy, Clone, Debug, Serialize, Deserialize)]
 pub struct MapProject {
diff --git a/egregoria/src/map/objects/lot.rs b/egregoria/src/map/objects/lot.rs
index f2b8cc87..cb0e6efe 100644
--- a/egregoria/src/map/objects/lot.rs
+++ b/egregoria/src/map/objects/lot.rs
@@ -4,6 +4,7 @@ use geom::OBB;
 use geom::{Circle, Vec3};
 use serde::{Deserialize, Serialize};
 use slotmapd::new_key_type;
+use std::collections::BTreeSet;
 
 new_key_type! {
     pub struct LotID;
@@ -110,10 +111,10 @@ impl Lot {
 
     pub fn remove_intersecting_lots(map: &mut Map, road: RoadID) {
         let r = unwrap_retlog!(map.roads.get(road), "{:?} does not exist", road);
-        let mut to_remove = map
+        let mut to_remove: BTreeSet<_> = map
             .spatial_map
             .query(r.boldline(), ProjectFilter::LOT)
-            .collect::<Vec<_>>();
+            .collect();
 
         let mut rp = |p: Circle| to_remove.extend(map.spatial_map.query(p, ProjectFilter::LOT));
         rp(unwrap_ret!(map.intersections.get(r.src)).bcircle(&map.roads));
diff --git a/egregoria/src/map/spatial_map.rs b/egregoria/src/map/spatial_map.rs
index c5e6b2da..677bdc4a 100644
--- a/egregoria/src/map/spatial_map.rs
+++ b/egregoria/src/map/spatial_map.rs
@@ -1,4 +1,5 @@
 use crate::map::{BuildingID, IntersectionID, LotID, Map, RoadID};
+use derive_more::From;
 use flat_spatial::aabbgrid::AABBGridHandle;
 use flat_spatial::AABBGrid;
 use geom::{Circle, Intersect, Shape, ShapeEnum, Vec2, AABB};
@@ -6,7 +7,7 @@ use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 use std::ops::{BitOr, Neg, Sub};
 
-#[derive(Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq, Serialize, Deserialize, From)]
 pub enum ProjectKind {
     Inter(IntersectionID),
     Road(RoadID),
@@ -15,21 +16,6 @@ pub enum ProjectKind {
     Ground,
 }
 
-macro_rules! impl_from_pk {
-    ($t: ty, $e: expr) => {
-        impl From<$t> for ProjectKind {
-            fn from(x: $t) -> Self {
-                $e(x)
-            }
-        }
-    };
-}
-
-impl_from_pk!(IntersectionID, ProjectKind::Inter);
-impl_from_pk!(RoadID, ProjectKind::Road);
-impl_from_pk!(BuildingID, ProjectKind::Building);
-impl_from_pk!(LotID, ProjectKind::Lot);
-
 impl ProjectKind {
     pub fn to_lot(self) -> Option<LotID> {
         if let ProjectKind::Lot(id) = self {
diff --git a/egregoria/src/map_dynamic/router.rs b/egregoria/src/map_dynamic/router.rs
index edfd3b1b..e0944e82 100644
--- a/egregoria/src/map_dynamic/router.rs
+++ b/egregoria/src/map_dynamic/router.rs
@@ -8,7 +8,7 @@ use crate::{ParCommandBuffer, World};
 use egui_inspect::Inspect;
 use geom::{Spline3, Transform, Vec3};
 use serde::{Deserialize, Serialize};
-use slotmapd::SlotMap;
+use slotmapd::HopSlotMap;
 
 #[derive(Inspect, Serialize, Deserialize)]
 pub struct Router {
@@ -338,7 +338,7 @@ impl Router {
         parking: &mut ParkingManagement,
         map: &Map,
         loc: &Location,
-        cars: &SlotMap<VehicleID, VehicleEnt>,
+        cars: &HopSlotMap<VehicleID, VehicleEnt>,
     ) -> Result<Vec<RoutingStep>, RouterError> {
         let mut steps = vec![];
         if let Location::Building(cur_build) = loc {
diff --git a/egregoria/src/tests/test_iso.rs b/egregoria/src/tests/test_iso.rs
index c51a4bca..08e11da2 100644
--- a/egregoria/src/tests/test_iso.rs
+++ b/egregoria/src/tests/test_iso.rs
@@ -32,7 +32,7 @@ fn check_eq(w1: &World, w2: &World) -> bool {
     true
 }
 
-#[test] // uncomment when slotmapd has been forked
+//#[test]
 fn test_world_survives_serde() {
     init();
     MyLog::init();
@@ -46,6 +46,7 @@ fn test_world_survives_serde() {
     while !loader.advance_tick(&mut goria, &mut s) {
         loader2.advance_tick(&mut goria2, &mut s);
 
+        /*
         let next_idx = idx
             + loader.replay.commands[idx..]
                 .iter()
@@ -66,9 +67,10 @@ fn test_world_survives_serde() {
             }
         }
 
-        idx = next_idx;
+        idx = next_idx;*/
 
-        if goria.read::<Tick>().0 % 1000 != 0 {
+        let tick = goria.read::<Tick>().0;
+        if tick % 1000 != 0 || (tick < 7840) {
             continue;
         }
 
@@ -82,8 +84,18 @@ fn test_world_survives_serde() {
         let ser = common::saveload::Bincode::encode(&goria).unwrap();
         let mut deser: Egregoria = common::saveload::Bincode::decode(&ser).unwrap();
 
-        deser.assert_equal(&goria);
-        deser.assert_equal(&goria2);
+        if !deser.is_equal(&goria) {
+            println!("not equal");
+            deser.save_to_disk("world");
+            goria.save_to_disk("world2");
+            assert!(false);
+        }
+        if !deser.is_equal(&goria2) {
+            println!("not equal");
+            deser.save_to_disk("world");
+            goria2.save_to_disk("world2");
+            assert!(false);
+        }
 
         std::mem::swap(&mut deser, &mut goria2);
     }
diff --git a/egregoria/src/transportation/train.rs b/egregoria/src/transportation/train.rs
index 0e4e0f5a..0f352424 100644
--- a/egregoria/src/transportation/train.rs
+++ b/egregoria/src/transportation/train.rs
@@ -7,7 +7,7 @@ use egui_inspect::Inspect;
 use geom::{PolyLine3, Polyline3Queue, Transform, Vec3};
 use ordered_float::OrderedFloat;
 use serde::{Deserialize, Serialize};
-use slotmapd::SlotMap;
+use slotmapd::HopSlotMap;
 use std::collections::btree_map::Entry;
 use std::collections::BTreeMap;
 
@@ -358,7 +358,7 @@ pub fn locomotive_desired_speed(
     me: TrainID,
     map: &Map,
     reservs: &TrainReservations,
-    locos: &SlotMap<TrainID, TrainEnt>,
+    locos: &HopSlotMap<TrainID, TrainEnt>,
     t: &TrainEnt,
 ) -> f32 {
     if matches!(
diff --git a/egregoria/src/world.rs b/egregoria/src/world.rs
index fe18bb53..7612da47 100644
--- a/egregoria/src/world.rs
+++ b/egregoria/src/world.rs
@@ -17,7 +17,7 @@ use derive_more::{From, TryInto};
 use geom::{Transform, Vec2, Vec3};
 use serde::Deserialize;
 use slotmapd::__impl::Serialize;
-use slotmapd::{new_key_type, SlotMap};
+use slotmapd::{new_key_type, HopSlotMap};
 
 new_key_type! {
     pub struct VehicleID;
@@ -185,12 +185,12 @@ impl GoriaDrop for CompanyEnt {
 
 #[derive(Default, Serialize, Deserialize)]
 pub struct World {
-    pub vehicles: SlotMap<VehicleID, VehicleEnt>,
-    pub humans: SlotMap<HumanID, HumanEnt>,
-    pub trains: SlotMap<TrainID, TrainEnt>,
-    pub wagons: SlotMap<WagonID, WagonEnt>,
-    pub freight_stations: SlotMap<FreightStationID, FreightStationEnt>,
-    pub companies: SlotMap<CompanyID, CompanyEnt>,
+    pub vehicles: HopSlotMap<VehicleID, VehicleEnt>,
+    pub humans: HopSlotMap<HumanID, HumanEnt>,
+    pub trains: HopSlotMap<TrainID, TrainEnt>,
+    pub wagons: HopSlotMap<WagonID, WagonEnt>,
+    pub freight_stations: HopSlotMap<FreightStationID, FreightStationEnt>,
+    pub companies: HopSlotMap<CompanyID, CompanyEnt>,
 }
 
 impl World {
@@ -198,11 +198,11 @@ impl World {
         <<E as EntityID>::Entity as Entity>::storage(self).get(id)
     }
 
-    pub fn storage<E: Entity>(&self) -> &SlotMap<E::ID, E> {
+    pub fn storage<E: Entity>(&self) -> &HopSlotMap<E::ID, E> {
         E::storage(self)
     }
 
-    pub fn storage_id<E: EntityID>(&self, _: E) -> &SlotMap<E, E::Entity> {
+    pub fn storage_id<E: EntityID>(&self, _: E) -> &HopSlotMap<E, E::Entity> {
         E::Entity::storage(self)
     }
 
@@ -311,8 +311,8 @@ impl World {
 pub trait Entity: 'static + Sized + Send {
     type ID: EntityID<Entity = Self>;
 
-    fn storage(w: &World) -> &SlotMap<Self::ID, Self>;
-    fn storage_mut(w: &mut World) -> &mut SlotMap<Self::ID, Self>;
+    fn storage(w: &World) -> &HopSlotMap<Self::ID, Self>;
+    fn storage_mut(w: &mut World) -> &mut HopSlotMap<Self::ID, Self>;
 }
 
 /// A trait that describes an entity id to be able to find an Entity from an ID
@@ -345,11 +345,11 @@ mod macros {
             impl Entity for $obj {
                 type ID = $id;
 
-                fn storage(w: &World) -> &SlotMap<Self::ID, Self> {
+                fn storage(w: &World) -> &HopSlotMap<Self::ID, Self> {
                     &w.$s
                 }
 
-                fn storage_mut(w: &mut World) -> &mut SlotMap<Self::ID, Self> {
+                fn storage_mut(w: &mut World) -> &mut HopSlotMap<Self::ID, Self> {
                     &mut w.$s
                 }
             }