diff --git a/lib/monet/src/lib.rs b/lib/monet/src/lib.rs
index 36786921..269f0007 100644
--- a/lib/monet/src/lib.rs
+++ b/lib/monet/src/lib.rs
@@ -129,6 +129,18 @@ impl Recipient<AddInstance> for Renderer {
     }}
 }
 
+#[derive(Compact, Clone)]
+pub struct AddSeveralInstances {pub scene_id: usize, pub batch_id: u16, pub positions: CVec<Instance>}
+
+impl Recipient<AddSeveralInstances> for Renderer {
+    fn receive(&mut self, msg: &AddSeveralInstances) -> Fate {match *msg {
+        AddSeveralInstances{scene_id, batch_id, ref positions} => {
+            self.scenes[scene_id].batches.get_mut(&batch_id).unwrap().instances.extend_from_slice(positions);
+            Fate::Live
+        }
+    }}
+}
+
 #[derive(Copy, Clone)]
 pub struct Project2dTo3d {pub scene_id: usize, pub position_2d: P2, pub requester: ID}
 
@@ -184,6 +196,7 @@ pub fn setup(system: &mut ActorSystem, renderer: Renderer) {
     system.add_unclearable_inbox::<Control, Renderer>();
     system.add_unclearable_inbox::<AddBatch, Renderer>();
     system.add_unclearable_inbox::<AddInstance, Renderer>();
+    system.add_unclearable_inbox::<AddSeveralInstances, Renderer>();
     system.add_unclearable_inbox::<UpdateThing, Renderer>();
     system.add_unclearable_inbox::<MoveEye, Renderer>();
     system.add_unclearable_inbox::<Project2dTo3d, Renderer>();
@@ -402,6 +415,7 @@ impl RenderContext {
             let vertices = glium::VertexBuffer::new(&self.window, &batch.prototype.vertices).unwrap();
             let indices = glium::IndexBuffer::new(&self.window, index::PrimitiveType::TrianglesList, &batch.prototype.indices).unwrap();
             let instances = glium::VertexBuffer::dynamic(&self.window, batch.instances.as_slice()).unwrap();
+            println!("rendering batch with {} instances", instances.len());
             target.draw((&vertices, instances.per_instance().unwrap()), &indices, &self.batch_program, &uniforms, &params).unwrap();
         }
 
diff --git a/src/game/lanes_and_cars/lane_rendering.rs b/src/game/lanes_and_cars/lane_rendering.rs
index fd78988d..1241f327 100644
--- a/src/game/lanes_and_cars/lane_rendering.rs
+++ b/src/game/lanes_and_cars/lane_rendering.rs
@@ -1,5 +1,5 @@
 use descartes::{Band, FiniteCurve, WithUniqueOrthogonal, Norm};
-use kay::{Actor, Individual, Recipient, RecipientAsSwarm, ActorSystem, Swarm, Fate};
+use kay::{Actor, CVec, Individual, Recipient, RecipientAsSwarm, ActorSystem, Swarm, Fate};
 use monet::{Instance, Thing, Vertex};
 use core::geometry::band_to_thing;
 use super::{Lane, TransferLane, InteractionKind};
@@ -72,24 +72,27 @@ impl Recipient<RenderToCollector> for Lane {
 
 use ::monet::RenderToScene;
 use ::monet::AddInstance;
+use ::monet::AddSeveralInstances;
 use ::monet::UpdateThing;
 
 impl Recipient<RenderToScene> for Lane {
     fn receive(&mut self, msg: &RenderToScene) -> Fate {match *msg {
         RenderToScene{renderer_id, scene_id} => {
-            for car in &self.cars {
+            let car_instances = self.cars.iter().map(|car| {
                 let position2d = self.path.along(*car.position);
                 let direction = self.path.direction_along(*car.position);
-                renderer_id << AddInstance{
-                    scene_id: scene_id,
-                    batch_id: 0,
-                    position: Instance{
-                        instance_position: [position2d.x, position2d.y, 0.0],
-                        instance_direction: [direction.x, direction.y],
-                        instance_color: [0.5, 0.5, 0.5]
-                    }
-                };
-            }
+                Instance{
+                    instance_position: [position2d.x, position2d.y, 0.0],
+                    instance_direction: [direction.x, direction.y],
+                    instance_color: [0.5, 0.5, 0.5]
+                }
+            }).collect::<CVec<_>>();
+
+            renderer_id << AddSeveralInstances{
+                scene_id: scene_id,
+                batch_id: 0,
+                positions: car_instances
+            };
 
             if ! self.interactions.iter().any(|inter| match inter.kind {InteractionKind::Next{..} => true, _ => false}) {
                 renderer_id << AddInstance{scene_id: scene_id, batch_id: 1333, position: Instance{
diff --git a/src/game/lanes_and_cars/mod.rs b/src/game/lanes_and_cars/mod.rs
index 89c27e07..77d56f53 100644
--- a/src/game/lanes_and_cars/mod.rs
+++ b/src/game/lanes_and_cars/mod.rs
@@ -113,7 +113,7 @@ const TRAFFIC_LOGIC_THROTTLING : usize = 60;
 impl Recipient<Tick> for Lane {
     fn receive(&mut self, msg: &Tick) -> Fate {match *msg{
         Tick{dt, current_tick} => {
-            self.in_construction += dt * 40.0;
+            self.in_construction += dt * 400.0;
 
             let do_traffic = current_tick % TRAFFIC_LOGIC_THROTTLING == self.id().instance_id as usize % TRAFFIC_LOGIC_THROTTLING;