diff --git a/overviewer_core/src/iterate.c b/overviewer_core/src/iterate.c
index 47e175b..4cc853c 100644
--- a/overviewer_core/src/iterate.c
+++ b/overviewer_core/src/iterate.c
@@ -22,9 +22,13 @@ static PyObject *chunk_mod = NULL;
 static PyObject *blockmap = NULL;
 static PyObject *known_blocks = NULL;
 static PyObject *transparent_blocks = NULL;
+static unsigned int max_blockid = 0;
+static unsigned int max_data = 0;
 
 PyObject *init_chunk_render(PyObject *self, PyObject *args) {
    
+    PyObject *tmp = NULL;
+    
     /* this function only needs to be called once, anything more should be
      * ignored */
     if (blockmap) {
@@ -53,6 +57,15 @@ PyObject *init_chunk_render(PyObject *self, PyObject *args) {
     if (!transparent_blocks)
         return NULL;
     
+    tmp = PyObject_GetAttrString(textures, "max_blockid");
+    if (!tmp)
+        return NULL;
+    max_blockid = PyInt_AsLong(tmp);
+    tmp = PyObject_GetAttrString(textures, "max_data");
+    if (!tmp)
+        return NULL;
+    max_data = PyInt_AsLong(tmp);
+    
     Py_RETURN_NONE;
 }
 
@@ -373,15 +386,13 @@ chunk_render(PyObject *self, PyObject *args) {
     
     for (state.x = 15; state.x > -1; state.x--) {
         for (state.y = 0; state.y < 16; state.y++) {
-            PyObject *blockid = NULL;
-            
+
             /* set up the render coordinates */
             state.imgx = xoff + state.x*12 + state.y*12;
             /* 128*12 -- offset for z direction, 15*6 -- offset for x */
             state.imgy = yoff - state.x*6 + state.y*6 + 128*12 + 15*6;
             
             for (state.z = 0; state.z < 128; state.z++) {
-                PyObject *tmp;
                 unsigned char ancilData;
                 
                 state.imgy -= 12;
@@ -399,14 +410,7 @@ chunk_render(PyObject *self, PyObject *args) {
                 if ((state.imgy >= imgsize1 + 24) || (state.imgy <= -24)) {
                     continue;
                 }
-
                 
-                /* decref'd on replacement *and* at the end of the z for block */
-                if (blockid) {
-                    Py_DECREF(blockid);
-                }
-                blockid = PyInt_FromLong(state.block);
-
                 /* check for occlusion */
                 if (render_mode_occluded(rendermode, state.x, state.y, state.z)) {
                     continue;
@@ -431,15 +435,12 @@ chunk_render(PyObject *self, PyObject *args) {
                     state.block_pdata = 0;
                 }
                 
-                tmp = PyTuple_New(2);
+                /* make sure our block info is in-bounds */
+                if (state.block >= max_blockid || ancilData >= max_data)
+                    continue;
                 
-                Py_INCREF(blockid); /* because SetItem steals */
-                PyTuple_SetItem(tmp, 0, blockid);
-                PyTuple_SetItem(tmp, 1, PyInt_FromLong(ancilData));
-                
-                /* this is a borrowed reference. no need to decref */
-                t = PyDict_GetItem(blockmap, tmp);
-                Py_DECREF(tmp);
+                /* get the texture */
+                t = PyList_GET_ITEM(blockmap, max_data * state.block + ancilData);
                 
                 /* if we found a proper texture, render it! */
                 if (t != NULL && t != Py_None)
@@ -470,11 +471,6 @@ chunk_render(PyObject *self, PyObject *args) {
                     }
                 }               
             }
-            
-            if (blockid) {
-                Py_DECREF(blockid);
-                blockid = NULL;
-            }
         }
     }
 
diff --git a/overviewer_core/textures.py b/overviewer_core/textures.py
index 39d4739..ae9d46f 100644
--- a/overviewer_core/textures.py
+++ b/overviewer_core/textures.py
@@ -423,7 +423,7 @@ def tintTexture(im, c):
 
 def generate_texture_tuple(img):
     """ This takes an image and returns the needed tuple for the
-    blockmap dictionary."""
+    blockmap array."""
     if img is None:
         return None
     return (img, generate_opaque_mask(img))
@@ -543,10 +543,14 @@ def loadLightColor():
 # placeholders that are generated in generate()
 texture_dimensions = None
 blockmap_generators = {}
-blockmap = {}
+blockmap = []
 biome_grass_texture = None
 
 known_blocks = set()
+used_datas = set()
+max_blockid = 0
+max_data = 0
+
 transparent_blocks = set()
 solid_blocks = set()
 fluid_blocks = set()
@@ -578,6 +582,7 @@ def material(blockid=[], data=[0], **kwargs):
             except TypeError:
                 return func(blockid, data)
         
+        used_datas.update(data)
         for block in blockid:
             # set the property sets appropriately
             known_blocks.update([block])
@@ -658,23 +663,26 @@ def generate(path=None,texture_size=24,bgc = (26,26,26,0),north_direction='lower
 
     # generate the blocks
     global blockmap, blockmap_generators
-    blockmap = {}
+    global max_blockid, max_data
+    max_blockid = max(known_blocks) + 1
+    max_data = max(used_datas) + 1
+    blockmap = [None] * max_blockid * max_data
+    
     for blockid, data in blockmap_generators:
         texgen = blockmap_generators[(blockid, data)]
         tex = texgen(blockid, data, north_direction)
-        blockmap[(blockid, data)] = generate_texture_tuple(tex)
+        blockmap[blockid * max_data + data] = generate_texture_tuple(tex)
     
     if texture_size != 24:
         # rescale biome textures.
         biome_grass_texture = biome_grass_texture.resize(texture_dimensions, Image.ANTIALIAS)
 
         # rescale the special block images
-        for blockid, data in iter(blockmap):
-            block = blockmap[(blockid,data)]
-            if block != None:
-                block = block[0]
+        for i, tex in enumerate(blockmap):
+            if tex != None:
+                block = tex[0]
                 scaled_block = block.resize(texture_dimensions, Image.ANTIALIAS)
-                blockmap[(blockid,data)] = generate_texture_tuple(scaled_block, blockid)
+                blockmap[i] = generate_texture_tuple(scaled_block)
 
 ##
 ## and finally: actual texture definitions