diff --git a/miniwin/src/d3drm/d3drmmesh.cpp b/miniwin/src/d3drm/d3drmmesh.cpp
index e487629e..de651797 100644
--- a/miniwin/src/d3drm/d3drmmesh.cpp
+++ b/miniwin/src/d3drm/d3drmmesh.cpp
@@ -64,8 +64,6 @@ HRESULT Direct3DRMMeshImpl::AddGroup(
 
 	m_groups.push_back(std::move(group));
 
-	UpdateBox(newIndex);
-
 	return DD_OK;
 }
 
@@ -281,19 +279,14 @@ void Direct3DRMMeshImpl::UpdateBox()
 	m_box.max = {-INF, -INF, -INF};
 
 	for (size_t i = 0; i < m_groups.size(); ++i) {
-		UpdateBox(i);
-	}
-}
-
-void Direct3DRMMeshImpl::UpdateBox(DWORD groupIndex)
-{
-	for (const D3DRMVERTEX& v : m_groups[groupIndex].vertices) {
-		m_box.min.x = std::min(m_box.min.x, v.position.x);
-		m_box.min.y = std::min(m_box.min.y, v.position.y);
-		m_box.min.z = std::min(m_box.min.z, v.position.z);
-		m_box.max.x = std::max(m_box.max.x, v.position.x);
-		m_box.max.y = std::max(m_box.max.y, v.position.y);
-		m_box.max.z = std::max(m_box.max.z, v.position.z);
+		for (const D3DRMVERTEX& v : m_groups[i].vertices) {
+			m_box.min.x = std::min(m_box.min.x, v.position.x);
+			m_box.min.y = std::min(m_box.min.y, v.position.y);
+			m_box.min.z = std::min(m_box.min.z, v.position.z);
+			m_box.max.x = std::max(m_box.max.x, v.position.x);
+			m_box.max.y = std::max(m_box.max.y, v.position.y);
+			m_box.max.z = std::max(m_box.max.z, v.position.z);
+		}
 	}
 }
 
diff --git a/miniwin/src/d3drm/d3drmviewport.cpp b/miniwin/src/d3drm/d3drmviewport.cpp
index 9e715f17..9c731f7f 100644
--- a/miniwin/src/d3drm/d3drmviewport.cpp
+++ b/miniwin/src/d3drm/d3drmviewport.cpp
@@ -212,7 +212,13 @@ bool IsBoxInFrustum(const D3DVECTOR corners[8], const Plane planes[6])
 	return true;
 }
 
-void Direct3DRMViewportImpl::CollectMeshesFromFrame(IDirect3DRMFrame* frame, D3DRMMATRIX4D parentMatrix)
+void Direct3DRMViewportImpl::CollectMeshesFromFrame(
+	IDirect3DRMFrame* frame,
+	D3DRMMATRIX4D parentMatrix,
+	std::vector<GeometryVertex>& verts,
+	std::vector<D3DRMVERTEX>& d3dVerts,
+	std::vector<DWORD>& faces
+)
 {
 	Direct3DRMFrameImpl* frameImpl = static_cast<Direct3DRMFrameImpl*>(frame);
 	D3DRMMATRIX4D localMatrix;
@@ -234,7 +240,7 @@ void Direct3DRMViewportImpl::CollectMeshesFromFrame(IDirect3DRMFrame* frame, D3D
 		IDirect3DRMFrame* childFrame = nullptr;
 		visual->QueryInterface(IID_IDirect3DRMFrame, (void**) &childFrame);
 		if (childFrame) {
-			CollectMeshesFromFrame(childFrame, worldMatrix);
+			CollectMeshesFromFrame(childFrame, worldMatrix, verts, d3dVerts, faces);
 			childFrame->Release();
 			visual->Release();
 			continue;
@@ -273,9 +279,12 @@ void Direct3DRMViewportImpl::CollectMeshesFromFrame(IDirect3DRMFrame* frame, D3D
 			DWORD vtxCount, faceCount, vpf, dataSize;
 			mesh->GetGroup(gi, &vtxCount, &faceCount, &vpf, &dataSize, nullptr);
 
-			std::vector<GeometryVertex> verts(dataSize * vpf);
-			std::vector<D3DRMVERTEX> d3dVerts(vtxCount);
-			std::vector<DWORD> faces(dataSize);
+			verts.reserve(dataSize);
+			verts.clear();
+			d3dVerts.resize(vtxCount);
+			d3dVerts.clear();
+			faces.resize(dataSize);
+			faces.clear();
 			mesh->GetVertices(gi, 0, vtxCount, d3dVerts.data());
 			mesh->GetGroup(gi, nullptr, nullptr, nullptr, nullptr, faces.data());
 
@@ -356,8 +365,11 @@ HRESULT Direct3DRMViewportImpl::RenderScene()
 		return status;
 	}
 
+	std::vector<GeometryVertex> verts;
+	std::vector<D3DRMVERTEX> d3dVerts;
+	std::vector<DWORD> faces;
 	ExtractFrustumPlanes(viewProj);
-	CollectMeshesFromFrame(m_rootFrame, identity);
+	CollectMeshesFromFrame(m_rootFrame, identity, verts, d3dVerts, faces);
 	return m_renderer->FinalizeFrame();
 }
 
diff --git a/miniwin/src/internal/d3drmmesh_impl.h b/miniwin/src/internal/d3drmmesh_impl.h
index 16e02087..d893e145 100644
--- a/miniwin/src/internal/d3drmmesh_impl.h
+++ b/miniwin/src/internal/d3drmmesh_impl.h
@@ -94,7 +94,6 @@ struct Direct3DRMMeshImpl : public Direct3DRMObjectBaseImpl<IDirect3DRMMesh> {
 
 private:
 	void UpdateBox();
-	void UpdateBox(DWORD groupIndex);
 
 	std::vector<MeshGroup> m_groups;
 	D3DRMBOX m_box;
diff --git a/miniwin/src/internal/d3drmviewport_impl.h b/miniwin/src/internal/d3drmviewport_impl.h
index 1d996d0d..3a5a244b 100644
--- a/miniwin/src/internal/d3drmviewport_impl.h
+++ b/miniwin/src/internal/d3drmviewport_impl.h
@@ -37,7 +37,13 @@ struct Direct3DRMViewportImpl : public Direct3DRMObjectBaseImpl<IDirect3DRMViewp
 private:
 	HRESULT RenderScene();
 	void CollectLightsFromFrame(IDirect3DRMFrame* frame, D3DRMMATRIX4D parentMatrix, std::vector<SceneLight>& lights);
-	void CollectMeshesFromFrame(IDirect3DRMFrame* frame, D3DRMMATRIX4D parentMatrix);
+	void CollectMeshesFromFrame(
+		IDirect3DRMFrame* frame,
+		D3DRMMATRIX4D parentMatrix,
+		std::vector<GeometryVertex>& verts,
+		std::vector<D3DRMVERTEX>& d3dVerts,
+		std::vector<DWORD>& faces
+	);
 	void UpdateProjectionMatrix();
 	Direct3DRMRenderer* m_renderer;
 	D3DCOLOR m_backgroundColor = 0xFF000000;