diff --git a/src/GuillotineBinPack.cpp b/src/GuillotineBinPack.cpp
index 5efbbf8a1..57dce4501 100644
--- a/src/GuillotineBinPack.cpp
+++ b/src/GuillotineBinPack.cpp
@@ -144,7 +144,9 @@ void GuillotineBinPack::Insert(TArray<RectSize> &rects, TArray<Rect> &dst, bool
 		usedRectangles.Push(newNode);
 
 		// Check that we're really producing correct packings here.
+#ifdef _DEBUG
 		assert(disjointRects.Add(newNode) == true);
+#endif
 	}
 }
 
@@ -355,8 +357,9 @@ Rect GuillotineBinPack::Insert(int width, int height, bool merge, FreeRectChoice
 	usedRectangles.Push(newRect);
 
 	// Check that we're really producing correct packings here.
+#ifdef _DEBUG
 	assert(disjointRects.Add(newRect) == true);
-
+#endif
 	return newRect;
 }
 
@@ -442,7 +445,9 @@ Rect GuillotineBinPack::FindPositionForNewNode(int width, int height, FreeRectCh
 			bestNode.height = height;
 			bestScore = INT_MIN;
 			*nodeIndex = i;
+#ifdef _DEBUG
 			assert(disjointRects.Disjoint(bestNode));
+#endif
 			break;
 		}
 		// If this is a perfect fit sideways, choose it.
@@ -470,7 +475,9 @@ Rect GuillotineBinPack::FindPositionForNewNode(int width, int height, FreeRectCh
 				bestNode.height = height;
 				bestScore = score;
 				*nodeIndex = i;
+#ifdef _DEBUG
 				assert(disjointRects.Disjoint(bestNode));
+#endif
 			}
 		}
 		// Does the rectangle fit sideways?
@@ -575,8 +582,10 @@ void GuillotineBinPack::SplitFreeRectAlongAxis(const Rect &freeRect, const Rect
 	if (right.width > 0 && right.height > 0)
 		freeRectangles.Push(right);
 
+#ifdef _DEBUG
 	assert(disjointRects.Disjoint(bottom));
 	assert(disjointRects.Disjoint(right));
+#endif
 }
 
 void GuillotineBinPack::MergeFreeList()
diff --git a/src/SkylineBinPack.cpp b/src/SkylineBinPack.cpp
index cb0be54e1..d63610370 100644
--- a/src/SkylineBinPack.cpp
+++ b/src/SkylineBinPack.cpp
@@ -69,7 +69,9 @@ void SkylineBinPack::Insert(TArray<RectSize> &rects, TArray<Rect> &dst)
 			int score2;
 			int index;
 			newNode = FindPositionForNewNodeMinWaste(rects[i].width, rects[i].height, score2, score1, index);
+#ifdef _DEBUG
 			assert(disjointRects.Disjoint(newNode));
+#endif
 			if (newNode.height != 0)
 			{
 				if (score1 < bestScore1 || (score1 == bestScore1 && score2 < bestScore2))
@@ -87,8 +89,8 @@ void SkylineBinPack::Insert(TArray<RectSize> &rects, TArray<Rect> &dst)
 			return;
 
 		// Perform the actual packing.
-		assert(disjointRects.Disjoint(bestNode));
 #ifdef _DEBUG
+		assert(disjointRects.Disjoint(bestNode));
 		disjointRects.Add(bestNode);
 #endif
 		AddSkylineLevel(bestSkylineIndex, bestNode);
@@ -103,7 +105,9 @@ Rect SkylineBinPack::Insert(int width, int height)
 	// First try to pack this rectangle into the waste map, if it fits.
 	Rect node = wasteMap.Insert(width, height, true, GuillotineBinPack::RectBestShortSideFit, 
 		GuillotineBinPack::SplitMaximizeArea);
+#ifdef _DEBUG
 	assert(disjointRects.Disjoint(node));
+#endif
 
 	if (node.height != 0)
 	{
@@ -113,8 +117,8 @@ Rect SkylineBinPack::Insert(int width, int height)
 		newNode.width = node.width;
 		newNode.height = node.height;
 		usedSurfaceArea += width * height;
-		assert(disjointRects.Disjoint(newNode));
 #ifdef _DEBUG
+		assert(disjointRects.Disjoint(newNode));
 		disjointRects.Add(newNode);
 #endif
 		return newNode;
@@ -190,7 +194,9 @@ void SkylineBinPack::AddWasteMapArea(int skylineNodeIndex, int width, int height
 		waste.width = rightSide - leftSide;
 		waste.height = y - skyLine[skylineNodeIndex].y;
 
+#ifdef _DEBUG
 		assert(disjointRects.Disjoint(waste));
+#endif
 		wasteMap.GetFreeRectangles().Push(waste);
 	}
 }
@@ -264,7 +270,9 @@ Rect SkylineBinPack::InsertBottomLeft(int width, int height)
 
 	if (bestIndex != -1)
 	{
+#ifdef _DEBUG
 		assert(disjointRects.Disjoint(newNode));
+#endif
 		// Perform the actual packing.
 		AddSkylineLevel(bestIndex, newNode);
 
@@ -300,7 +308,9 @@ Rect SkylineBinPack::FindPositionForNewNodeBottomLeft(int width, int height, int
 				newNode.y = y;
 				newNode.width = width;
 				newNode.height = height;
+#ifdef _DEBUG
 				assert(disjointRects.Disjoint(newNode));
+#endif
 			}
 		}
 /*		if (RectangleFits(i, height, width, y))
@@ -331,7 +341,9 @@ Rect SkylineBinPack::InsertMinWaste(int width, int height)
 
 	if (bestIndex != -1)
 	{
+#ifdef _DEBUG
 		assert(disjointRects.Disjoint(newNode));
+#endif
 		// Perform the actual packing.
 		AddSkylineLevel(bestIndex, newNode);
 
@@ -369,7 +381,9 @@ Rect SkylineBinPack::FindPositionForNewNodeMinWaste(int width, int height, int &
 				newNode.y = y;
 				newNode.width = width;
 				newNode.height = height;
+#ifdef _DEBUG
 				assert(disjointRects.Disjoint(newNode));
+#endif
 			}
 		}
 /*		if (RectangleFits(i, height, width, y, wastedArea))