diff --git a/src/mceditlib/test/time_exportimport.py b/src/mceditlib/bench/time_exportimport.py
similarity index 100%
rename from src/mceditlib/test/time_exportimport.py
rename to src/mceditlib/bench/time_exportimport.py
diff --git a/src/mceditlib/test/time_fill.py b/src/mceditlib/bench/time_fill.py
similarity index 100%
rename from src/mceditlib/test/time_fill.py
rename to src/mceditlib/bench/time_fill.py
diff --git a/src/mceditlib/test/time_getsetblocks.py b/src/mceditlib/bench/time_getsetblocks.py
similarity index 100%
rename from src/mceditlib/test/time_getsetblocks.py
rename to src/mceditlib/bench/time_getsetblocks.py
diff --git a/src/mceditlib/test/time_loadsave.py b/src/mceditlib/bench/time_loadsave.py
similarity index 100%
rename from src/mceditlib/test/time_loadsave.py
rename to src/mceditlib/bench/time_loadsave.py
diff --git a/src/mceditlib/test/time_nbt.py b/src/mceditlib/bench/time_nbt.py
similarity index 100%
rename from src/mceditlib/test/time_nbt.py
rename to src/mceditlib/bench/time_nbt.py
diff --git a/src/mceditlib/bench/time_relight_manmade.py b/src/mceditlib/bench/time_relight_manmade.py
new file mode 100644
index 0000000..d8564e8
--- /dev/null
+++ b/src/mceditlib/bench/time_relight_manmade.py
@@ -0,0 +1,52 @@
+from timeit import timeit
+
+import numpy
+from mceditlib.selection import BoundingBox
+
+from mceditlib.worldeditor import WorldEditor
+from mceditlib.test import templevel
+from mceditlib import relight
+
+
+def manmade_relight():
+    world = templevel.TempLevel("AnvilWorld")
+    dim = world.getDimension()
+    stationEditor = WorldEditor("test_files/station.schematic")
+    station = stationEditor.getDimension()
+
+    times = 1
+    boxes = []
+
+    for x in range(times):
+        for z in range(times):
+            origin = (x * station.bounds.width, 54, z * station.bounds.length)
+            boxes.append(BoundingBox(origin, station.bounds.size))
+            dim.copyBlocks(station, station.bounds, origin, create=True)
+
+    box = reduce(lambda a, b: a.union(b), boxes)
+
+    positions = []
+    for cx, cz in box.chunkPositions():
+        for cy in box.sectionPositions(cx, cz):
+            positions.append((cx, cy, cz))
+
+    poses = iter(positions)
+
+    def do_relight():
+        cx, cy, cz = poses.next()
+        print "Relighting section %s..." % ((cx, cy, cz),)
+        indices = numpy.indices((16, 16, 16), numpy.uint32)
+        indices.shape = 3, 16*16*16
+        indices += ([cx], [cy], [cz])
+        x, y, z = indices
+        relight.updateLightsByCoord(dim, x, y, z)
+
+    sectionCount = 5
+    t = timeit(do_relight, number=sectionCount)
+    print "Relight manmade building: %d chunk-sections in %.02f seconds (%dms per section)" % (sectionCount, t, 1000 * t / sectionCount)
+
+if __name__ == '__main__':
+    manmade_relight()
+
+
+
diff --git a/src/mceditlib/bench/time_relight_natural.py b/src/mceditlib/bench/time_relight_natural.py
new file mode 100644
index 0000000..3ab056c
--- /dev/null
+++ b/src/mceditlib/bench/time_relight_natural.py
@@ -0,0 +1,38 @@
+import numpy
+from mceditlib.worldeditor import WorldEditor
+from timeit import timeit
+
+from mceditlib.test import templevel
+from mceditlib import relight
+
+# run me with the source checkout as the working dir so I can find the test_files folder.
+
+def natural_relight():
+    world = templevel.TempLevel("AnvilWorld")
+    dim = world.getDimension()
+    positions = []
+    for cx, cz in dim.chunkPositions():
+        chunk = dim.getChunk(cx, cz)
+        for cy in chunk.sectionPositions():
+            positions.append((cx, cy, cz))
+
+    poses = iter(positions)
+
+    def do_relight():
+        cx, cy, cz = poses.next()
+        print "Relighting section %s..." % ((cx, cy, cz),)
+        indices = numpy.indices((16, 16, 16), numpy.uint32)
+        indices.shape = 3, 16*16*16
+        indices += ([cx], [cy], [cz])
+        x, y, z = indices
+        relight.updateLightsByCoord(dim, x, y, z)
+
+    sectionCount = 5
+    t = timeit(do_relight, number=sectionCount)
+    print "Relight natural terrain: %d chunk-sections in %.02f seconds (%dms per section)" % (sectionCount, t, 1000 * t / sectionCount)
+
+if __name__ == '__main__':
+    natural_relight()
+
+
+
diff --git a/src/mceditlib/test/time_storagechain.py b/src/mceditlib/bench/time_storagechain.py
similarity index 100%
rename from src/mceditlib/test/time_storagechain.py
rename to src/mceditlib/bench/time_storagechain.py
diff --git a/src/mceditlib/fakechunklevel.py b/src/mceditlib/fakechunklevel.py
index 249bd63..2bd4c30 100644
--- a/src/mceditlib/fakechunklevel.py
+++ b/src/mceditlib/fakechunklevel.py
@@ -59,7 +59,7 @@ class FakeChunkData(object):
         arrays or its rootTag. Alternately, just set `chunk.dirty = True`
 
         needsLighting is deprecated; Use the updateLights= argument
-        of setBlocks and other editing functions, or call updateLights(level, x, y, z) to
+        of setBlocks and other editing functions, or call updateLightsByCoord(level, x, y, z) to
         explicitly update lights yourself.
 
         """
diff --git a/src/mceditlib/multi_block.py b/src/mceditlib/multi_block.py
index 8d14aa6..248683e 100644
--- a/src/mceditlib/multi_block.py
+++ b/src/mceditlib/multi_block.py
@@ -356,7 +356,7 @@ def setBlocks(dimension, x, y, z,
         chunk.dirty = True
 
     if updateLights:
-        relight.updateLights(dimension, x, y, z)
+        relight.updateLightsByCoord(dimension, x, y, z)
 
 
 def setChunkBlocks(chunk, x, y, z,
diff --git a/src/mceditlib/operations/block_fill.py b/src/mceditlib/operations/block_fill.py
index 1e13ac8..2444734 100644
--- a/src/mceditlib/operations/block_fill.py
+++ b/src/mceditlib/operations/block_fill.py
@@ -140,7 +140,7 @@ class FillBlocksOperation(Operation):
                 z = coords[1] + (cz << 4)
                 x = coords[2] + (cx << 4)
 
-                mceditlib.relight.updateLights(self.dimension, x, y, z)
+                mceditlib.relight.updateLightsByCoord(self.dimension, x, y, z)
 
         def include(ref):
             return ref.Position not in self.selection
diff --git a/src/mceditlib/relight/__init__.py b/src/mceditlib/relight/__init__.py
new file mode 100644
index 0000000..935b988
--- /dev/null
+++ b/src/mceditlib/relight/__init__.py
@@ -0,0 +1,28 @@
+"""
+    __init__
+"""
+from __future__ import absolute_import, division, print_function, unicode_literals
+import logging
+
+log = logging.getLogger(__name__)
+
+def setMethod(name):
+    if name == "pure":
+        from mceditlib.relight import pure_python
+        setModule(pure_python)
+    if name == "cython":
+        from mceditlib.relight import with_cython
+        setModule(with_cython)
+    if name == "setBlocks":
+        from mceditlib.relight import with_setblocks
+        setModule(with_setblocks)
+    if name == "sections":
+        from mceditlib.relight import with_sections
+        setModule(with_sections)
+
+def setModule(mod):
+    global updateLightsByCoord, updateLightsInSelection
+    updateLightsByCoord = mod.updateLightsByCoord
+    updateLightsInSelection = mod.updateLightsInSelection
+
+setMethod("pure")
\ No newline at end of file
diff --git a/src/mceditlib/relight/pure_python.py b/src/mceditlib/relight/pure_python.py
new file mode 100644
index 0000000..d232af1
--- /dev/null
+++ b/src/mceditlib/relight/pure_python.py
@@ -0,0 +1,98 @@
+"""
+    pure_python
+"""
+from __future__ import absolute_import, division, print_function, unicode_literals
+import logging
+
+log = logging.getLogger(__name__)
+
+def updateLightsByCoord(dim, x, y, z):
+    for i in range(len(x)):
+        updateLights(dim, x[i], y[i], z[i])
+
+def neighbors(x, y, z):
+    yield x-1, y, z
+    yield x+1, y, z
+    yield x, y-1, z
+    yield x, y+1, z
+    yield x, y, z-1
+    yield x, y, z+1
+
+
+def updateLights(dim, x, y, z):
+    # import pdb; pdb.set_trace()
+    previousLight = dim.getBlockLight(x, y, z)
+    light = dim.getBlock(x, y, z).brightness
+    dim.setBlockLight(x, y, z, light)
+
+    drawLight(dim, x, y, z)
+
+    if previousLight < light:
+        spreadLight(dim, x, y, z)
+
+    if previousLight > light:
+        fadeLight(dim, x, y, z, previousLight)
+
+def getOpacity(dim, x, y, z):
+    return max(1, dim.getBlock(x, y, z).opacity)
+
+def drawLight(dim, x, y, z):
+    opacity = getOpacity(dim, x, y, z)
+
+    for nx, ny, nz in neighbors(x, y, z):
+        adjacentLight = dim.getBlockLight(nx, ny, nz)
+        if adjacentLight - opacity > dim.getBlockLight(x, y, z):
+            dim.setBlockLight(x, y, z, adjacentLight - opacity)
+
+def spreadLight(dim, x, y, z):
+    light = dim.getBlockLight(x, y, z)
+    if light <= 0:
+        return
+
+    for nx, ny, nz in neighbors(x, y, z):
+
+        # xxx cast to int because one of these is a numpy.uint8 and
+        # light - opacity rolls over to a large number.
+        adjacentLight = int(dim.getBlockLight(nx, ny, nz))
+        adjacentOpacity = getOpacity(dim, nx, ny, nz)
+        newLight = light - adjacentOpacity
+        # If the adjacent cell already has the "correct" light value, stop.
+        if newLight > adjacentLight:
+            dim.setBlockLight(nx, ny, nz, newLight)
+            spreadLight(dim, nx, ny, nz)
+
+
+def fadeLight(dim, x, y, z, previousLight):
+    fadedCells = findFadedCells(dim, x, y, z, previousLight)
+    for x, y, z in fadedCells:
+        dim.setBlockLight(x, y, z, dim.getBlock(x, y, z).brightness)
+        # dim.setBlock(x, y, z, "glass")
+    for x, y, z in fadedCells:
+        drawLight(dim, x, y, z)
+    for x, y, z in fadedCells:
+        spreadLight(dim, x, y, z)
+
+
+def relCoords(ox, oy, oz, coords):
+    for x, y, z, l in coords:
+        yield x - ox, y - oy, z - oz
+
+
+def findFadedCells(dim, ox, oy, oz, oPreviousLight):
+    foundCells = set()
+    toScan = [(ox, oy, oz, oPreviousLight)]
+
+    while len(toScan):
+        x, y, z, previousLight = toScan.pop(0)
+        for nx, ny, nz in neighbors(x, y, z):
+
+            adjacentLight = int(dim.getBlockLight(nx, ny, nz))
+            adjacentOpacity = getOpacity(dim, nx, ny, nz)
+            if previousLight - adjacentOpacity <= 0:
+                continue
+            if previousLight - adjacentOpacity == adjacentLight:
+                if (nx, ny, nz) not in foundCells:
+                    toScan.append((nx, ny, nz, adjacentLight))
+                    foundCells.add((nx, ny, nz))
+
+    return foundCells
diff --git a/src/mceditlib/relight/with_cython.pyx b/src/mceditlib/relight/with_cython.pyx
new file mode 100644
index 0000000..e69de29
diff --git a/src/mceditlib/relight/with_sections.py b/src/mceditlib/relight/with_sections.py
new file mode 100644
index 0000000..b4bdee1
--- /dev/null
+++ b/src/mceditlib/relight/with_sections.py
@@ -0,0 +1,88 @@
+"""
+    with_sections
+"""
+from __future__ import absolute_import, division, print_function, unicode_literals
+import logging
+import numpy
+from mceditlib.exceptions import ChunkNotPresent
+
+log = logging.getLogger(__name__)
+
+def updateLightsInSelection(dim, selection):
+    for cx, cz in selection.chunkPositions():
+        for cy in selection.sectionPositions(cx, cz):
+            updateLightsInSection(dim, cx, cy, cz)
+
+def updateLightsByCoord(dim, x, y, z):
+    """
+
+    :param dim:
+    :param x:
+    :param y:
+    :param z:
+    :return:
+    """
+
+    # gross.
+    cx = numpy.asanyarray(x) >> 4
+    cy = numpy.asanyarray(y) >> 4
+    cz = numpy.asanyarray(z) >> 4
+
+    cx = numpy.unique(cx)
+    cy = numpy.unique(cy)
+    cz = numpy.unique(cz)
+
+    for i in range(len(cx)):
+        updateLightsInSection(dim, cx[i], cy[i], cz[i])
+
+
+def updateLightsInSection(dim, cx, cy, cz):
+    try:
+        chunk = dim.getChunk(cx, cz)
+    except ChunkNotPresent:
+        return
+
+    section = chunk.getSection(cy)
+    if section is None:
+        return
+
+    light = section.BlockLight
+    blocks = section.Blocks
+
+    # Reset all lights to block brightness values
+    # xxx if BlockLight
+    light[:] = dim.blocktypes.brightness[blocks]
+
+    # Get all block opacities only once
+    opacity = dim.blocktypes.opacity[blocks]
+
+    directions = ((0, -1),
+                  (0, 1),
+                  (1, -1),
+                  (1, 1),
+                  (2, -1),
+                  (2, 1))
+
+    for axis, direction in directions:
+        leftSlices = [None, None, None]
+        rightSlices = [None, None, None]
+        if direction == 1:
+            leftSlices[axis] = slice(None, -1)
+            rightSlices[axis] = slice(1, None)
+        else:
+            leftSlices[axis] = slice(1, None)
+            rightSlices[axis] = slice(None, -1)
+
+        leftLight = light[leftSlices]
+        rightOpacity = opacity[rightSlices]
+
+        newRightLight = leftLight - rightOpacity
+        # BlockLight is unsigned. Lights that were zero or less are now huge, so clip light values
+        newRightLight.view('int8').clip(0, 15, newRightLight)
+
+        changed = newRightLight != leftLight
+
+
+
+
+
diff --git a/src/mceditlib/relight.py b/src/mceditlib/relight/with_setblocks.py
similarity index 97%
rename from src/mceditlib/relight.py
rename to src/mceditlib/relight/with_setblocks.py
index ce293de..a00fc6a 100644
--- a/src/mceditlib/relight.py
+++ b/src/mceditlib/relight/with_setblocks.py
@@ -140,7 +140,12 @@ def updateHeightmap(dimension, x, y, z):
 
 ENABLE_LIGHTING = True
 
-def updateLights(dimension, x, y, z):
+def updateLightsInSelection(dimension, selection):
+    # xxx slow
+    x, y, z = numpy.array(selection.positions).T
+    return updateLightsByCoord(dimension, x, y, z)
+
+def updateLightsByCoord(dimension, x, y, z):
     """
 
     :param dimension:
diff --git a/src/mceditlib/test/time_relight.py b/src/mceditlib/test/time_relight.py
deleted file mode 100644
index f50d499..0000000
--- a/src/mceditlib/test/time_relight.py
+++ /dev/null
@@ -1,37 +0,0 @@
-from mceditlib.worldeditor import WorldEditor
-from timeit import timeit
-
-import templevel
-
-#import logging
-#logging.basicConfig(level=logging.INFO)
-
-def natural_relight():
-    world = templevel.TempLevel("AnvilWorld")
-    dim = world.getDimension()
-    t = timeit(lambda: dim.generateLights(dim.chunkPositions()), number=1)
-    print "Relight natural terrain: %d chunks in %.02f seconds (%.02fms per chunk)" % (dim.chunkCount, t,
-                                                                                       t / world.chunkCount * 1000)
-
-
-def manmade_relight():
-    t = templevel.TempLevel("TimeRelight", createFunc=lambda f:WorldEditor(f, create=True))
-
-    world = t
-    station = WorldEditor("test_files/station.schematic")
-
-    times = 2
-
-    for x in range(times):
-        for z in range(times):
-            world.copyBlocksFrom(station, station.bounds, (x * station.Width, 63, z * station.Length), create=True)
-
-    t = timeit(lambda: world.generateLights(world.chunkPositions), number=1)
-    print "Relight manmade building: %d chunks in %.02f seconds (%.02fms per chunk)" % (world.chunkCount, t, t / world.chunkCount * 1000)
-
-if __name__ == '__main__':
-    natural_relight()
-    manmade_relight()
-
-
-
diff --git a/src/mceditlib/worldeditor.py b/src/mceditlib/worldeditor.py
index 8056bce..7625586 100644
--- a/src/mceditlib/worldeditor.py
+++ b/src/mceditlib/worldeditor.py
@@ -849,6 +849,45 @@ class WorldEditorDimension(object):
                     array[y & 0xf, z & 0xf, x & 0xf] = value
             chunk.dirty = True
 
+    def getLight(self, arrayName, x, y, z, default=0):
+        cx = x >> 4
+        cy = y >> 4
+        cz = z >> 4
+        if self.containsChunk(cx, cz):
+            chunk = self.getChunk(cx, cz)
+            sec = chunk.getSection(cy)
+            if sec:
+                array = getattr(sec, arrayName)
+                if array is not None:
+                    return array[y & 0xf, z & 0xf, x & 0xf]
+        return default
+
+    def setLight(self, arrayName, x, y, z, value):
+        cx = x >> 4
+        cy = y >> 4
+        cz = z >> 4
+        if self.containsChunk(cx, cz):
+            chunk = self.getChunk(cx, cz)
+            sec = chunk.getSection(cy, create=True)
+            if sec:
+                array = getattr(sec, arrayName)
+                assert array is not None
+                if array is not None:
+                    array[y & 0xf, z & 0xf, x & 0xf] = value
+            chunk.dirty = True
+
+    def getBlockLight(self, x, y, z, default=0):
+        return self.getLight("BlockLight", x, y, z, default)
+
+    def setBlockLight(self, x, y, z, value):
+        return self.setLight("BlockLight", x, y, z, value)
+
+    def getSkyLight(self, x, y, z, default=0):
+        return self.getLight("SkyLight", x, y, z, default)
+
+    def setSkyLight(self, x, y, z, value):
+        return self.setLight("SkyLight", x, y, z, value)
+
     def getBiomeID(self, x, z, default=0):
         cx = x >> 4
         cz = z >> 4