diff --git a/gorge.js b/gorge.js
index 8efdec0..3984394 100644
--- a/gorge.js
+++ b/gorge.js
@@ -73,11 +73,9 @@ function applyGlobalProdBonus(cost) {
   for (let effect of effects["prod-all"]) {
 
     if (ownedUpgrades[effect.parent]) {
-      cost = effect.apply(cost);
+      effect.apply(cost);
     }
   }
-
-  return cost;
 }
 
 function calculateProductivity() {
@@ -99,44 +97,42 @@ function applyProductivityMultipliers(type, cost) {
   for (let effect of effects["prod"]) {
 
     if (ownedUpgrades[effect.parent] && effect.target == type) {
-      cost = effect.apply(cost);
+      effect.apply(cost);
     }
   }
 
   for (let effect of effects["helper"]) {
 
     if (ownedUpgrades[effect.parent] && effect.helped == type) {
-      cost = effect.apply(cost, belongings[effect.helper].count);
+      effect.apply(cost, belongings[effect.helper].count);
     }
   }
-
-  return cost;
 }
 
 function productivityOf(type) {
   let baseProd = makeCost(buildings[type].prod);
 
-  baseProd = applyProductivityMultipliers(type, baseProd);
+  applyProductivityMultipliers(type, baseProd);
 
-  baseProd = applyGlobalProdBonus(baseProd);
+  applyGlobalProdBonus(baseProd);
 
-  baseProd = scaleCost(baseProd, belongings[type].count);
+  scaleCost(baseProd, belongings[type].count);
 
   return baseProd;
 }
 
 function makeCost(source) {
   const empty = mapObject(resourceTypes, () => 0);
-  return deepFreeze({...empty, ...source});
+  return {...empty, ...source};
 }
 
 function addCost(cost1, cost2) {
-  return deepFreeze(Object.keys(resourceTypes).reduce((o, k) => ({ ...o, [k]: cost1[k] + cost2[k]}), {}));
+  return Object.keys(resourceTypes).reduce((o, k) => {o[k] += cost2[k]; return o;}, cost1);
 }
 
 function scaleCost(cost, scale) {
   if (typeof(scale) != "number") console.log(scale)
-  return deepFreeze(Object.keys(resourceTypes).reduce((o, k) => ({ ...o, [k]: cost[k] * scale}), {}));
+  return Object.keys(resourceTypes).reduce((o, k) => {o[k] *= scale; return o;}, cost);
 }
 
 function costOfBuilding(type, count = 1) {