diff --git a/spine-lua/Animation.lua b/spine-lua/Animation.lua
index 9f33f3144..205427150 100644
--- a/spine-lua/Animation.lua
+++ b/spine-lua/Animation.lua
@@ -413,9 +413,16 @@ function Animation.AttachmentTimeline.new ()
 		end
 
 		local attachmentName = self.attachmentNames[frameIndex]
-		local attachment
-		if attachmentName then attachment = skeleton:getAttachment(self.slotName, attachmentName) end
-		skeleton:findSlot(self.slotName):setAttachment(attachment)
+    local slot = skeleton.slotsByName[self.slotName]
+    if attachmentName then
+      if not slot.attachment then
+        slot:setAttachment(skeleton:getAttachment(self.slotName, attachmentName))
+      elseif slot.attachment.name ~= attachmentName then
+        slot:setAttachment(skeleton:getAttachment(self.slotName, attachmentName))
+      end
+    else
+      slot:setAttachment(nil)
+    end
 	end
 
 	return self
diff --git a/spine-lua/Skeleton.lua b/spine-lua/Skeleton.lua
index 2626de810..b19ad86c9 100644
--- a/spine-lua/Skeleton.lua
+++ b/spine-lua/Skeleton.lua
@@ -35,6 +35,7 @@ function Skeleton.new (skeletonData)
 		data = skeletonData,
 		bones = {},
 		slots = {},
+    slotsByName = {},
 		drawOrder = {}
 	}
 
@@ -73,13 +74,10 @@ function Skeleton.new (skeletonData)
 		return nil
 	end
 
-	function self:findSlot (slotName)
-		if not slotName then error("slotName cannot be nil.", 2) end
-		for i,slot in ipairs(self.slots) do
-			if slot.data.name == slotName then return slot end
-		end
-		return nil
-	end
+  function self:findSlot (slotName)
+    if not slotName then error("slotName cannot be nil.", 2) end
+    return slotsByName[slotName]
+  end
 
 	function self:setSkin (skinName)
 		local newSkin
@@ -106,7 +104,7 @@ function Skeleton.new (skeletonData)
 	function self:getAttachment (slotName, attachmentName)
 		if not slotName then error("slotName cannot be nil.", 2) end
 		if not attachmentName then error("attachmentName cannot be nil.", 2) end
-		local slotIndex = self.data:findSlotIndex(slotName)
+		local slotIndex = skeletonData.slotNameIndices[slotName]
 		if slotIndex == -1 then error("Slot not found: " .. slotName, 2) end
 		if self.skin then
 			local attachment = self.skin:getAttachment(slotIndex, attachmentName)
@@ -147,6 +145,7 @@ function Skeleton.new (skeletonData)
 		local bone = self.bones[spine.utils.indexOf(skeletonData.bones, slotData.boneData)]
 		local slot = Slot.new(slotData, self, bone)
 		table.insert(self.slots, slot)
+        self.slotsByName[slot.data.name] = slot
 		table.insert(self.drawOrder, slot)
 	end
 
diff --git a/spine-lua/SkeletonData.lua b/spine-lua/SkeletonData.lua
index db776b153..531f9613e 100644
--- a/spine-lua/SkeletonData.lua
+++ b/spine-lua/SkeletonData.lua
@@ -28,6 +28,7 @@ function SkeletonData.new ()
 	local self = {
 		bones = {},
 		slots = {},
+    slotNameIndices = {},
 		skins = {},
 		animations = {}
 	}
@@ -58,10 +59,7 @@ function SkeletonData.new ()
 
 	function self:findSlotIndex (slotName)
 		if not slotName then error("slotName cannot be nil.", 2) end
-		for i,slot in ipairs(self.slots) do
-			if slot.name == slotName then return i end
-		end
-		return -1
+		return slotNameIndices[slotName] or -1
 	end
 
 	function self:findSkin (skinName)
diff --git a/spine-lua/SkeletonJson.lua b/spine-lua/SkeletonJson.lua
index a837ceb13..0125d5833 100644
--- a/spine-lua/SkeletonJson.lua
+++ b/spine-lua/SkeletonJson.lua
@@ -29,7 +29,6 @@ local SlotData = require "spine-lua.SlotData"
 local Skin = require "spine-lua.Skin"
 local AttachmentLoader = require "spine-lua.AttachmentLoader"
 local Animation = require "spine-lua.Animation"
-
 local TIMELINE_SCALE = "scale"
 local TIMELINE_ROTATE = "rotate"
 local TIMELINE_TRANSLATE = "translate"
@@ -102,8 +101,9 @@ function SkeletonJson.new (attachmentLoader)
 				end
 
 				slotData.attachmentName = slotMap["attachment"]
-
-				table.insert(skeletonData.slots, slotData)
+        table.insert(skeletonData.slots, slotData)
+        skeletonData.slotNameIndices[slotData.name] = #skeletonData.slots
+        
 			end
 		end
 
@@ -113,7 +113,7 @@ function SkeletonJson.new (attachmentLoader)
 			for skinName,skinMap in pairs(map) do
 				local skin = Skin.new(skinName)
 				for slotName,slotMap in pairs(skinMap) do
-					local slotIndex = skeletonData:findSlotIndex(slotName)
+					local slotIndex = skeletonData.slotNameIndices[slotName]
 					for attachmentName,attachmentMap in pairs(slotMap) do
 						local attachment = readAttachment(attachmentName, attachmentMap, self.scale)
 						if attachment then
@@ -213,7 +213,7 @@ function SkeletonJson.new (attachmentLoader)
 		local slotsMap = map["slots"]
 		if slotsMap then
 			for slotName,timelineMap in pairs(slotsMap) do
-				local slotIndex = skeletonData:findSlotIndex(slotName)
+				local slotIndex = skeletonData.slotNameIndices[slotName]
 
 				for timelineName,values in pairs(timelineMap) do
 					if timelineName == TIMELINE_COLOR then