diff --git a/fastlib/col/arraylist.h b/fastlib/col/arraylist.h
index 97c4984707..ecbbdadda4 100644
--- a/fastlib/col/arraylist.h
+++ b/fastlib/col/arraylist.h
@@ -16,10 +16,10 @@
 /**
  * Fast expandable array with debug-mode bounds checking.
  *
- * This has roughly similar features to std::vector.  However, instead of
- * assuming the data type has a copy constructor, we assume it can be
- * "relocated" to another memory address using realloc.
- * The primary case where this assumption would be false is if objects have
+ * This has roughly similar features to std::vector.  However, an ArrayList
+ * assumes that all objects can be relocated by just doing a shallow move
+ * with realloc, without performing a deep copy on every element.
+ * This means you cannot use an ArrayList if objects have
  * pointers to fields within themselves -- this isn't a very common
  * programming practice.  Like std::vector, it is unwise to have
  * external pointers to objects inside this array, if you expect that the
@@ -41,7 +41,7 @@
  * ArrayList<MyType> list;
  * list.Init();
  * while (some_condition) {
- *    list.AddBack()->Init(arguments, for, MyType);
+ *    list.AddBack()->Init(x, y, z);
  * }
  * @endcode
  *
@@ -51,14 +51,21 @@
  * ArrayList<MyType> list;
  * list.Init(55);
  * for (int i = 0; i < 55; i++) {
- *   list[i].Init(arguments, for, MyType);
+ *   list[i].Init(x, y, z);
  * }
  * @endcode
  *
+ * In addition, ArrayList has all the definitions necessary for the object
+ * traversal system, so it is suitable for use with THOR's automatic
+ * serialization and deserialization.
+ *
  */
 template<typename TElement>
 class ArrayList {
  public:
+  /**
+   * The element type.
+   */
   typedef TElement Element;
 
  private:
@@ -208,6 +215,9 @@ class ArrayList {
   /**
    * Steals the contents of another ArrayList, initializing this ArrayList and
    * destructing the other ArrayList.
+   *
+   * WARNING: If the other ArrayList falls out of scope without being
+   * reinitialized, the program will fail.
    */
   void StealDestruct(ArrayList* other) {
     DEBUG_ASSERT_MSG(size_ == BIG_BAD_NUMBER, "reinitialization not allowed");
diff --git a/fastlib/thor/cachearray.h b/fastlib/thor/cachearray.h
index 7b163b403c..cbe0f4246f 100644
--- a/fastlib/thor/cachearray.h
+++ b/fastlib/thor/cachearray.h
@@ -103,11 +103,9 @@ class CacheArray {
    * "locked" blocks!  This maximum should be 32 for most use cases, with 64
    * giving a nice balance between efficiency and memory usage -- given the
    * worst-case of 32 used blocks, the mean search time for an empty FIFO
-   * entry is two, and only 64 blocks are forced into RAM.
+   * entry is about three, and only 48 blocks are forced into RAM.
    */
   static const int FIFO_SIZE = 64;
-  /** Bitmask for doing modulo FIFO_SIZE. */
-  static const int FIFO_MASK = (FIFO_SIZE-1);
 
  protected:
   /** The metadata array, but adjusted (see how it is used in code). */
diff --git a/fastlib/thor/cachearray_impl.h b/fastlib/thor/cachearray_impl.h
index 9817a147c9..a8085a8419 100644
--- a/fastlib/thor/cachearray_impl.h
+++ b/fastlib/thor/cachearray_impl.h
@@ -258,22 +258,33 @@ typename CacheArray<T>::Element* CacheArray<T>::HandleCacheMiss_(
   // unlocked item -- the most likely case is that the first item in the
   // fifo is non-negative (i.e. it exists) and it's most likely not locked
   for (;;) {
-    fifo_index_ = (fifo_index_+1) & FIFO_MASK;
+    if (unlikely(fifo_index_ == 0)) {
+      fifo_index_ = FIFO_SIZE;
+    }
+
+    fifo_index_--;
     victim = fifo_[fifo_index_];
+
     if (unlikely(victim < 0)) {
       break;
     }
+
     victim_metadata = adjusted_metadatas_ + victim;
+
     if (unlikely(victim_metadata->lock_count != 0)) {
+      // the block was locked
       continue;
     }
+
     DEBUG_ASSERT(victim_metadata->data != NULL);
     if (BlockDevice::can_write(mode_)) {
       cache_->StopWrite(victim);
     } else {
       cache_->StopRead(victim);
     }
+
     victim_metadata->data = NULL;
+
     break;
   }
 
diff --git a/fastlib/thor/gnp.h b/fastlib/thor/gnp.h
index 2059a5c780..317fd9433c 100644
--- a/fastlib/thor/gnp.h
+++ b/fastlib/thor/gnp.h
@@ -63,10 +63,11 @@ class ThorVectorPoint {
    * with Init.
    *
    * @param param ignored
+   * @param index the index of the point, ignored
    * @param data the vector data read from file
    */
   template<typename Param>
-  void Set(const Param& param, const Vector& data) {
+  void Set(const Param& param, index_t index, const Vector& data) {
     vec_.CopyValues(data);
   }
 };
@@ -77,8 +78,6 @@ struct BlankDelta {
  public:
   template<typename Param>
   void Init(const Param& param) {}
-  template<typename Param>
-  void ApplyDelta(const Param& param, const BlankDelta& other) {}
 };
 
 struct BlankQPostponed {
diff --git a/fastlib/thor/thor_utils_impl.h b/fastlib/thor/thor_utils_impl.h
index 6068e5466a..48f438c7a9 100644
--- a/fastlib/thor/thor_utils_impl.h
+++ b/fastlib/thor/thor_utils_impl.h
@@ -104,9 +104,9 @@ index_t thor::ReadPointsMaster(
     } else if (is_done) {
       break;
     } else {
-      CacheWrite<Point> point(&points_array,
-          points_array.AllocD(rpc::rank(), 1));
-      point->Set(param, vector);
+      index_t i = points_array.AllocD(rpc::rank(), 1);
+      CacheWrite<Point> point(&points_array, i);
+      point->Set(param, i, vector);
       n_points++;
     }
   }
diff --git a/fastlib/u/garryb/nbr/affinity.cc b/fastlib/u/garryb/nbr/affinity.cc
index a26c35c9f9..ab4f7ff7c5 100644
--- a/fastlib/u/garryb/nbr/affinity.cc
+++ b/fastlib/u/garryb/nbr/affinity.cc
@@ -207,7 +207,7 @@ struct AffinityCommon {
       info_.rho = param.pref;
     }
 
-    void Set(const Param& param, const Vector& data) {
+    void Set(const Param& param, index_t index, const Vector& data) {
       vec_.CopyValues(data);
       // Randomly prime points to be exemplars.
       if (math::Random(0.0, 1.0) < param.prime) {