Add "preload instances" setting, disabling this may help if you are low on memory.

apps/openmw/mwworld/cellpreloader.cpp

@@ -45,7 +45,7 @@ namespace MWWorld
     {
     public:
         /// Constructor to be called from the main thread.
-        PreloadItem(MWWorld::CellStore* cell, Resource::SceneManager* sceneManager, Resource::BulletShapeManager* bulletShapeManager, Resource::KeyframeManager* keyframeManager, Terrain::World* terrain)
+        PreloadItem(MWWorld::CellStore* cell, Resource::SceneManager* sceneManager, Resource::BulletShapeManager* bulletShapeManager, Resource::KeyframeManager* keyframeManager, Terrain::World* terrain, bool preloadInstances)
             : mIsExterior(cell->getCell()->isExterior())
             , mX(cell->getCell()->getGridX())
             , mY(cell->getCell()->getGridY())
@@ -53,6 +53,7 @@ namespace MWWorld
             , mBulletShapeManager(bulletShapeManager)
             , mKeyframeManager(keyframeManager)
             , mTerrain(terrain)
+            , mPreloadInstances(preloadInstances)
         {
             ListModelsVisitor visitor (mMeshes);
             if (cell->getState() == MWWorld::CellStore::State_Loaded)
@@ -84,8 +85,16 @@ namespace MWWorld
                     std::string mesh  = *it;
                     mesh = Misc::ResourceHelpers::correctActorModelPath(mesh, mSceneManager->getVFS());
 
+                    if (mPreloadInstances)
+                    {
                         mPreloadedObjects.push_back(mSceneManager->cacheInstance(mesh));
                         mPreloadedObjects.push_back(mBulletShapeManager->cacheInstance(mesh));
+                    }
+                    else
+                    {
+                        mPreloadedObjects.push_back(mSceneManager->getTemplate(mesh));
+                        mPreloadedObjects.push_back(mBulletShapeManager->getShape(mesh));
+                    }
 
                     size_t slashpos = mesh.find_last_of("/\\");
                     if (slashpos != std::string::npos && slashpos != mesh.size()-1)
@@ -132,6 +141,7 @@ namespace MWWorld
         Resource::BulletShapeManager* mBulletShapeManager;
         Resource::KeyframeManager* mKeyframeManager;
         Terrain::World* mTerrain;
+        bool mPreloadInstances;
 
         // keep a ref to the loaded objects to make sure it stays loaded as long as this cell is in the preloaded state
         std::vector<osg::ref_ptr<const osg::Object> > mPreloadedObjects;
@@ -168,6 +178,7 @@ namespace MWWorld
         , mExpiryDelay(0.0)
         , mMinCacheSize(0)
         , mMaxCacheSize(0)
+        , mPreloadInstances(true)
     {
     }
 
@@ -220,7 +231,7 @@ namespace MWWorld
                 return;
         }
 
-        osg::ref_ptr<PreloadItem> item (new PreloadItem(cell, mResourceSystem->getSceneManager(), mBulletShapeManager, mResourceSystem->getKeyframeManager(), mTerrain));
+        osg::ref_ptr<PreloadItem> item (new PreloadItem(cell, mResourceSystem->getSceneManager(), mBulletShapeManager, mResourceSystem->getKeyframeManager(), mTerrain, mPreloadInstances));
         mWorkQueue->addWorkItem(item);
 
         mPreloadCells[cell] = PreloadEntry(timestamp, item);
@@ -260,6 +271,11 @@ namespace MWWorld
         mMaxCacheSize = num;
     }
 
+    void CellPreloader::setPreloadInstances(bool preload)
+    {
+        mPreloadInstances = preload;
+    }
+
     unsigned int CellPreloader::getMaxCacheSize() const
     {
         return mMaxCacheSize;

apps/openmw/mwworld/cellpreloader.hpp

@@ -44,6 +44,9 @@ namespace MWWorld
         /// The maximum number of preloaded cells.
         void setMaxCacheSize(unsigned int num);
 
+        /// Enables the creation of instances in the preloading thread.
+        void setPreloadInstances(bool preload);
+
         unsigned int getMaxCacheSize() const;
 
         void setWorkQueue(osg::ref_ptr<SceneUtil::WorkQueue> workQueue);
@@ -56,6 +59,7 @@ namespace MWWorld
         double mExpiryDelay;
         unsigned int mMinCacheSize;
         unsigned int mMaxCacheSize;
+        bool mPreloadInstances;
 
         struct PreloadEntry
         {

apps/openmw/mwworld/scene.cpp

@@ -478,6 +478,7 @@ namespace MWWorld
         mPreloader->setExpiryDelay(Settings::Manager::getFloat("preload cell expiry delay", "Cells"));
         mPreloader->setMinCacheSize(Settings::Manager::getInt("preload cell cache min", "Cells"));
         mPreloader->setMaxCacheSize(Settings::Manager::getInt("preload cell cache max", "Cells"));
+        mPreloader->setPreloadInstances(Settings::Manager::getBool("preload instances", "Cells"));
     }
 
     Scene::~Scene()

files/settings-default.cfg

@@ -52,6 +52,11 @@ preload doors = true
 # Preloading distance threshold
 preload distance = 1000
 
+# Controls whether or not the nodes/collision shapes are pre-"instanced" (i.e. cloned) when a cell is preloaded.
+# Enabling this option slightly reduces the time it takes to transition into a preloaded cell, but also results in higher memory usage
+# proportional to the number of cells that are preloaded.
+preload instances = true
+
 # The minimum amount of cells in the preload cache before unused cells start to get thrown out (see "preload cell expiry delay").
 # This value should be lower or equal to 'preload cell cache max'.
 preload cell cache min = 12