diff --git a/apps/openmw/mwmechanics/aicombat.cpp b/apps/openmw/mwmechanics/aicombat.cpp
index 6a1ab68d86..19c3fa2f3a 100644
--- a/apps/openmw/mwmechanics/aicombat.cpp
+++ b/apps/openmw/mwmechanics/aicombat.cpp
@@ -49,8 +49,6 @@ namespace MWMechanics
             //MWWorld::Class::get(actor).getCreatureStats(actor).setAttackingOrSpell(true);
         }
         ESM::Position pos = actor.getRefData().getPosition();
-        const ESM::Pathgrid *pathgrid =
-            MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*actor.getCell()->mCell);
 
         float xCell = 0;
         float yCell = 0;
@@ -74,20 +72,19 @@ namespace MWMechanics
         mTimer2 = mTimer2 + duration;
 
         if(!mPathFinder.isPathConstructed())
-            mPathFinder.buildPath(start, dest, pathgrid, xCell, yCell, true);
+            mPathFinder.buildPath(start, dest, actor.getCell(), true);
         else
         {
             if(mTimer2 > 0.25)
             {
                 mTimer2 = 0;
-                mPathFinder2.buildPath(start, dest, pathgrid, xCell, yCell, true);
+                mPathFinder2.buildPath(start, dest, actor.getCell(), true);
                 ESM::Pathgrid::Point lastPt = mPathFinder.getPath().back();
                 if(mPathFinder2.getPathSize() < mPathFinder.getPathSize() ||
                     (dest.mX - lastPt.mX)*(dest.mX - lastPt.mX)+(dest.mY - lastPt.mY)*(dest.mY - lastPt.mY)+(dest.mZ - lastPt.mZ)*(dest.mZ - lastPt.mZ) > 200*200)
                     mPathFinder = mPathFinder2;
             }
         }
-        ESM::Pathgrid::Point lastPt = mPathFinder.getPath().back();
 
         mPathFinder.checkPathCompleted(pos.pos[0],pos.pos[1],pos.pos[2]);
 
diff --git a/apps/openmw/mwmechanics/aiescort.cpp b/apps/openmw/mwmechanics/aiescort.cpp
index 35f9f19932..0d44dd6fce 100644
--- a/apps/openmw/mwmechanics/aiescort.cpp
+++ b/apps/openmw/mwmechanics/aiescort.cpp
@@ -85,8 +85,6 @@ namespace MWMechanics
         MWWorld::Ptr player = MWBase::Environment::get().getWorld()->getPlayerPtr();
         ESM::Position pos = actor.getRefData().getPosition();
         bool cellChange = actor.getCell()->mCell->mData.mX != cellX || actor.getCell()->mCell->mData.mY != cellY;
-        const ESM::Pathgrid *pathgrid =
-            MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*actor.getCell()->mCell);
 
         if(actor.getCell()->mCell->mData.mX != player.getCell()->mCell->mData.mX)
         {
@@ -136,7 +134,7 @@ namespace MWMechanics
             start.mY = pos.pos[1];
             start.mZ = pos.pos[2];
 
-            mPathFinder.buildPath(start, dest, pathgrid, xCell, yCell, true);
+            mPathFinder.buildPath(start, dest, actor.getCell(), true);
         }
 
         if(mPathFinder.checkPathCompleted(pos.pos[0],pos.pos[1],pos.pos[2]))
diff --git a/apps/openmw/mwmechanics/aifollow.cpp b/apps/openmw/mwmechanics/aifollow.cpp
index 399504ff1d..a711ebe7cd 100644
--- a/apps/openmw/mwmechanics/aifollow.cpp
+++ b/apps/openmw/mwmechanics/aifollow.cpp
@@ -81,10 +81,7 @@ bool MWMechanics::AiFollow::execute (const MWWorld::Ptr& actor,float duration)
             ESM::Pathgrid::Point start;
             start.mX = pos.pos[0];
             start.mY = pos.pos[1];
-            start.mZ = pos.pos[2];
-
-            const ESM::Pathgrid *pathgrid =
-                MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*actor.getCell()->mCell);
+            start.mZ = pos.pos[2];
 
             float xCell = 0;
             float yCell = 0;
@@ -94,7 +91,7 @@ bool MWMechanics::AiFollow::execute (const MWWorld::Ptr& actor,float duration)
                 xCell = actor.getCell()->mCell->mData.mX * ESM::Land::REAL_SIZE;
                 yCell = actor.getCell()->mCell->mData.mY * ESM::Land::REAL_SIZE;
             }
-            mPathFinder.buildPath(start, dest, pathgrid, xCell, yCell, true);
+            mPathFinder.buildPath(start, dest, actor.getCell(), true);
         }
         mStuckTimer = 0;
         mStuckPos = pos;
diff --git a/apps/openmw/mwmechanics/aitravel.cpp b/apps/openmw/mwmechanics/aitravel.cpp
index 73b38dd130..24a61310b0 100644
--- a/apps/openmw/mwmechanics/aitravel.cpp
+++ b/apps/openmw/mwmechanics/aitravel.cpp
@@ -61,7 +61,6 @@ namespace MWMechanics
             }
         }
 
-        const ESM::Pathgrid *pathgrid = world->getStore().get<ESM::Pathgrid>().search(*cell);
         bool cellChange = cell->mData.mX != cellX || cell->mData.mY != cellY;
         if(!mPathFinder.isPathConstructed() || cellChange)
         {
@@ -86,7 +85,7 @@ namespace MWMechanics
             start.mY = pos.pos[1];
             start.mZ = pos.pos[2];
 
-            mPathFinder.buildPath(start, dest, pathgrid, xCell, yCell, true);
+            mPathFinder.buildPath(start, dest, actor.getCell(), true);
         }
 
         if(mPathFinder.checkPathCompleted(pos.pos[0], pos.pos[1], pos.pos[2]))
diff --git a/apps/openmw/mwmechanics/aiwander.cpp b/apps/openmw/mwmechanics/aiwander.cpp
index 7df88c076b..353121a3ec 100644
--- a/apps/openmw/mwmechanics/aiwander.cpp
+++ b/apps/openmw/mwmechanics/aiwander.cpp
@@ -213,7 +213,7 @@ namespace MWMechanics
                 start.mY = pos.pos[1];
                 start.mZ = pos.pos[2];
 
-                mPathFinder.buildPath(start, dest, mPathgrid, mXCell, mYCell, false);
+                mPathFinder.buildPath(start, dest, actor.getCell(), false);
 
                 if(mPathFinder.isPathConstructed())
                 {
diff --git a/apps/openmw/mwmechanics/pathfinding.cpp b/apps/openmw/mwmechanics/pathfinding.cpp
index c8bc9b49cf..86019fe549 100644
--- a/apps/openmw/mwmechanics/pathfinding.cpp
+++ b/apps/openmw/mwmechanics/pathfinding.cpp
@@ -6,7 +6,6 @@
 #include "OgreMath.h"
 
 #include <boost/graph/dijkstra_shortest_paths.hpp>
-#include <boost/graph/adjacency_list.hpp>
 
 namespace
 {
@@ -136,8 +135,8 @@ namespace
 namespace MWMechanics
 {
     PathFinder::PathFinder()
+        :mIsPathConstructed(false),mIsGraphConstructed(false)
     {
-        mIsPathConstructed = false;
     }
 
     void PathFinder::clearPath()
@@ -147,10 +146,19 @@ namespace MWMechanics
         mIsPathConstructed = false;
     }
 
+    void PathFinder::buildPathgridGraph(const ESM::Pathgrid* pathGrid,float xCell, float yCell)
+    {
+        mGraph = buildGraph(pathGrid, xCell, yCell);
+        mIsGraphConstructed = true;
+    }
+
     void PathFinder::buildPath(const ESM::Pathgrid::Point &startPoint, const ESM::Pathgrid::Point &endPoint,
-                               const ESM::Pathgrid *pathGrid, float xCell, float yCell, bool allowShortcuts)
+                               const MWWorld::CellStore* cell, bool allowShortcuts)
     {
         mPath.clear();
+        if(mCell != cell) mIsGraphConstructed = false;
+        mCell = cell;
+
         if(allowShortcuts)
         {
             if(MWBase::Environment::get().getWorld()->castRay(startPoint.mX, startPoint.mY, startPoint.mZ,
@@ -160,13 +168,24 @@ namespace MWMechanics
 
         if(!allowShortcuts)
         {
+            const ESM::Pathgrid *pathGrid =
+                MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*mCell->mCell);
+            float xCell = 0;
+            float yCell = 0;
+
+            if (mCell->isExterior())
+            {
+                xCell = mCell->mCell->mData.mX * ESM::Land::REAL_SIZE;
+                yCell = mCell->mCell->mData.mY * ESM::Land::REAL_SIZE;
+            }
             int startNode = getClosestPoint(pathGrid, startPoint.mX - xCell, startPoint.mY - yCell,startPoint.mZ);
             int endNode = getClosestPoint(pathGrid, endPoint.mX - xCell, endPoint.mY - yCell, endPoint.mZ);
 
             if(startNode != -1 && endNode != -1)
             {
-                PathGridGraph graph = buildGraph(pathGrid, xCell, yCell);
-                mPath = findPath(startNode, endNode, graph);
+                if(!mIsGraphConstructed) buildPathgridGraph(pathGrid, xCell, yCell);
+
+                mPath = findPath(startNode, endNode, mGraph);
 
                 if(!mPath.empty())
                 {
diff --git a/apps/openmw/mwmechanics/pathfinding.hpp b/apps/openmw/mwmechanics/pathfinding.hpp
index f9c2c5cc77..6870314910 100644
--- a/apps/openmw/mwmechanics/pathfinding.hpp
+++ b/apps/openmw/mwmechanics/pathfinding.hpp
@@ -3,6 +3,12 @@
 
 #include <components/esm/loadpgrd.hpp>
 #include <list>
+#include <boost/graph/adjacency_list.hpp>
+
+namespace MWWorld
+{
+    class CellStore;
+}
 
 namespace MWMechanics
 {
@@ -12,9 +18,11 @@ namespace MWMechanics
             PathFinder();
 
             void clearPath();
+
+            void buildPathgridGraph(const ESM::Pathgrid* pathGrid,float xCell = 0, float yCell = 0);
+
             void buildPath(const ESM::Pathgrid::Point &startPoint, const ESM::Pathgrid::Point &endPoint,
-                           const ESM::Pathgrid* pathGrid, float xCell = 0, float yCell = 0,
-                           bool allowShortcuts = true);
+                           const MWWorld::CellStore* cell, bool allowShortcuts = true);
 
             bool checkPathCompleted(float x, float y, float z);
             ///< \Returns true if the last point of the path has been reached.
@@ -45,6 +53,13 @@ namespace MWMechanics
         private:
             std::list<ESM::Pathgrid::Point> mPath;
             bool mIsPathConstructed;
+
+            typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS,
+                boost::property<boost::vertex_index_t, int, ESM::Pathgrid::Point>, boost::property<boost::edge_weight_t, float> >
+                PathGridGraph;
+            PathGridGraph mGraph;
+            bool mIsGraphConstructed;
+            const MWWorld::CellStore* mCell;
     };
 }