diff --git a/search_functions.lua b/search_functions.lua
index d665b5f..1f11476 100644
--- a/search_functions.lua
+++ b/search_functions.lua
@@ -52,9 +52,23 @@ function biome_lib:find_open_side(pos)
 	return nil
 end
 
--- "Record" the chunks being generated by the core mapgen
+-- "Record" the map chunks being generated by the core mapgen,
+-- split into individual mapblocks to reduce lag
 
 minetest.register_on_generated(function(minp, maxp, blockseed)
-	biome_lib.blocklist_aircheck[#biome_lib.blocklist_aircheck + 1] = { minp, maxp }
-	biome_lib.blocklist_no_aircheck[#biome_lib.blocklist_no_aircheck + 1] = { minp, maxp }
+	for x = 0, 5 do
+		local minx = minp.x + x*16
+		for y = 0, 5 do
+			local miny = minp.y + y*16
+			for z = 0, 5 do
+				local minz = minp.z + z*16
+
+				local bmin = {x=minx, y=miny, z=minz}
+				local bmax = {x=minx + 15, y=miny + 15, z=minz + 15}
+
+				biome_lib.blocklist_aircheck[#biome_lib.blocklist_aircheck + 1] = { bmin, bmax }
+				biome_lib.blocklist_no_aircheck[#biome_lib.blocklist_no_aircheck + 1] = { bmin, bmax }
+			end
+		end
+	end
 end)