diff --git a/overviewer_core/world.py b/overviewer_core/world.py
index 59339c7..f1261f5 100644
--- a/overviewer_core/world.py
+++ b/overviewer_core/world.py
@@ -1164,40 +1164,26 @@ class RegionSet(object):
     def _get_blockdata_v113(self, section, unrecognized_block_types):
         # Translate each entry in the palette to a 1.2-era (block, data) int pair.
         num_palette_entries = len(section['Palette'])
-        palette_translated = [] # (block, data) pairs, num_palette_entries in length
-        palette_block_counts = [] # ints, num_palette_entries in length
-        unrecognized_palette_entries = []
+        translated_blocks = numpy.zeros((num_palette_entries,), dtype=numpy.uint16) # block IDs
+        translated_data = numpy.zeros((num_palette_entries,), dtype=numpy.uint8) # block data
         for i in range(num_palette_entries):
             key = section['Palette'][i]
-            palette_block_counts.append(0)
             try:
-                palette_translated.append(self._get_block(key))
-            except KeyError as e:
-                # Unknown block type? Track it, treat it as air, and move on.
-                unrecognized_palette_entries.append(i)
-                palette_translated.append(self._blockmap['minecraft:air'])
+                translated_blocks[i], translated_data[i] = self._get_block(key)
+            except KeyError:
+                pass    # We already have initialised arrays with 0 (= air)
 
         # Turn the BlockStates array into a 16x16x16 numpy matrix of shorts.
         blocks = numpy.zeros((4096,), dtype=numpy.uint16)
         data = numpy.zeros((4096,), dtype=numpy.uint8)
         block_states = self._packed_longarray_to_shorts(section['BlockStates'], 4096)
-        for i in range(4096):
-            palette_index = block_states[i]
-            (blocks[i], data[i]) = palette_translated[palette_index]
-            palette_block_counts[palette_index] += 1
+        blocks[::1] = translated_blocks[block_states]
+        data[::1] = translated_data[block_states]
 
         # Turn the Data array into a 16x16x16 matrix, same as SkyLight
         blocks  = blocks.reshape((16, 16, 16))
         data = data.reshape((16, 16, 16))
 
-        for i in unrecognized_palette_entries:
-            if palette_block_counts[i] > 0:
-                palette_entry = section['Palette'][i]
-                k = palette_entry['Name']
-                if 'Properties' in palette_entry:
-                    k += " %s" % str(palette_entry['Properties'])
-                unrecognized_block_types[k] = unrecognized_block_types.get(k, 0) + palette_block_counts[i]
-
         return (blocks, data)
 
     def _get_blockdata_v112(self, section):