diff --git a/spec/System/TestCommon_spec.lua b/spec/System/TestCommon_spec.lua
index 61a848e14e..4ff1906d83 100644
--- a/spec/System/TestCommon_spec.lua
+++ b/spec/System/TestCommon_spec.lua
@@ -5,7 +5,7 @@ describe("Common", function()
 			function ParentClass:ConstructorTestParentClass()
 				return self
 			end
-			local ChildClass = newClass("ConstructorTestProblemChildClass", "ConstructorTestParentClass")
+			local ChildClass = newClass("ConstructorTestProblemChild", "ConstructorTestParentClass")
 			function ChildClass:ConstructorTestProblemChild()
 				-- Intentionally does not call self:ConstructorTestParentClass()
 				return self
@@ -40,7 +40,7 @@ describe("Common", function()
 				return self
 			end
 
-			local ChildClass = newClass("ConstructorTestProblemChildClass", "ConstructorTestParentClass")
+			local ChildClass = newClass("ConstructorTestProblemChild", "ConstructorTestParentClass")
 			function ChildClass:ConstructorTestProblemChild()
 				self.ConstructorTestParentClass()
 				return self
diff --git a/src/Classes/ModDB.lua b/src/Classes/ModDB.lua
index c71599b5a0..ffaf1e5ea5 100644
--- a/src/Classes/ModDB.lua
+++ b/src/Classes/ModDB.lua
@@ -135,7 +135,7 @@ end
 
 function ModDBClass:SumInternal(context, modType, cfg, flags, keywordFlags, source, ...)
 	local result = 0
-	local globalLimits = { }
+	local globalLimits
 	for i = 1, select('#', ...) do
 		local modList = self.mods[select(i, ...)]
 		if modList then
@@ -143,6 +143,9 @@ function ModDBClass:SumInternal(context, modType, cfg, flags, keywordFlags, sour
 				local mod = modList[i]
 				if mod.type == modType and band(flags, mod.flags) == mod.flags and MatchKeywordFlags(keywordFlags, mod.keywordFlags) and (not source or ( mod.source and mod.source:match("[^:]+") == source )) then
 					if mod[1] then
+						if not globalLimits then
+							globalLimits = {}
+						end
 						local value = context:EvalMod(mod, cfg, globalLimits) or 0
 						result = result + value
 					else
@@ -161,7 +164,7 @@ end
 function ModDBClass:MoreInternal(context, cfg, flags, keywordFlags, source, ...)
 	local result = 1
 	local modPrecision = nil
-	local globalLimits = { }
+	local globalLimits
 	for i = 1, select('#', ...) do
 		local modList = self.mods[select(i, ...)]
 		local modResult = 1 --The more multipliers for each mod are computed to the nearest percent then applied.
@@ -171,6 +174,9 @@ function ModDBClass:MoreInternal(context, cfg, flags, keywordFlags, source, ...)
 				if mod.type == "MORE" and band(flags, mod.flags) == mod.flags and MatchKeywordFlags(keywordFlags, mod.keywordFlags) and (not source or mod.source:match("[^:]+") == source) then
 					local value
 					if mod[1] then
+						if not globalLimits then
+							globalLimits = {}
+						end
 						value = context:EvalMod(mod, cfg, globalLimits) or 0
 					else
 						value = mod.value or 0
@@ -270,7 +276,7 @@ function ModDBClass:ListInternal(context, result, cfg, flags, keywordFlags, sour
 end
 
 function ModDBClass:TabulateInternal(context, result, modType, cfg, flags, keywordFlags, source, ...)
-	local globalLimits = { }
+	local globalLimits
 	for i = 1, select('#', ...) do
 		local modName = select(i, ...)
 		local modList = self.mods[modName]
@@ -280,6 +286,9 @@ function ModDBClass:TabulateInternal(context, result, modType, cfg, flags, keywo
 				if (mod.type == modType or not modType) and band(flags, mod.flags) == mod.flags and MatchKeywordFlags(keywordFlags, mod.keywordFlags) and (not source or mod.source:match("[^:]+") == source) then
 					local value
 					if mod[1] then
+						if not globalLimits then
+							globalLimits = {}
+						end
 						value = context:EvalMod(mod, cfg, globalLimits)
 					else
 						value = mod.value
diff --git a/src/Modules/CalcSetup.lua b/src/Modules/CalcSetup.lua
index 5b2d481a3c..780fd7e7c0 100644
--- a/src/Modules/CalcSetup.lua
+++ b/src/Modules/CalcSetup.lua
@@ -114,8 +114,21 @@ function calcs.initModDB(env, modDB)
 	modDB.conditions["Effective"] = env.mode_effective
 end
 
-function calcs.buildModListForNode(env, node)
-	local modList = new("ModList"):ModList()
+-- Recycle a modlist so that we do not allocate many tables for each node.
+local function resetModList(list)
+	for i = #list, 1, -1 do
+		list[i] = nil
+	end
+	list.multipliers = wipeTable(list.multipliers)
+	list.conditions = wipeTable(list.conditions)
+	list.actor = wipeTable(list.actor)
+	list.parent = false
+	return list
+end
+
+---@param reuse table|nil A ModList to recycle instead of allocating. Only safe when the caller discards the result.
+function calcs.buildModListForNode(env, node, reuse)
+	local modList = reuse and resetModList(reuse) or new("ModList"):ModList()
 	if node.type == "Keystone" then
 		modList:AddMod(node.keystoneMod)
 	else
@@ -123,51 +136,118 @@ function calcs.buildModListForNode(env, node)
 	end
 
 	-- Run first pass radius jewels
-	for _, rad in pairs(env.radiusJewelList) do
-		if rad.type == "Other" and rad.nodes[node.id] and rad.nodes[node.id].type ~= "Mastery" then
-			rad.func(node, modList, rad.data)
+	for i = 1, #env.radiusJewelList do
+		local rad = env.radiusJewelList[i]
+		if rad.type == "Other" then
+			local radNode = rad.nodes[node.id]
+			if radNode and radNode.type ~= "Mastery" then
+				rad.func(node, modList, rad.data)
+			end
 		end
 	end
 
-	if modList:Flag(nil, "PassiveSkillHasNoEffect") or (env.allocNodes[node.id] and modList:Flag(nil, "AllocatedPassiveSkillHasNoEffect")) then
+	-- prefilter the modlist so that every :Flag() call does not have to go through the entire mod list
+	local hasNoEffect, hasAllocNoEffect, hasScale, hasOtherEffect, hasExtraSkill, hasExplode
+	for i = 1, #modList do
+		local name = modList[i].name
+		if name == "PassiveSkillHasNoEffect" then
+			hasNoEffect = true
+		elseif name == "AllocatedPassiveSkillHasNoEffect" then
+			hasAllocNoEffect = true
+		elseif name == "PassiveSkillEffect" then
+			hasScale = true
+		elseif name == "PassiveSkillHasOtherEffect" then
+			hasOtherEffect = true
+		elseif name == "ExtraSkill" then
+			hasExtraSkill = true
+		elseif name == "CanExplode" then
+			hasExplode = true
+		end
+	end
+
+	if (hasNoEffect and modList:Flag(nil, "PassiveSkillHasNoEffect")) or (env.allocNodes[node.id] and (hasAllocNoEffect and modList:Flag(nil, "AllocatedPassiveSkillHasNoEffect"))) then
 		wipeTable(modList)
+		hasScale = false
+		hasOtherEffect = nil
+		hasExtraSkill = nil
+		hasExplode = nil
 	end
 
 	-- Apply effect scaling
-	local scale = calcLib.mod(modList, nil, "PassiveSkillEffect")
-	if scale ~= 1 then
-		local scaledList = new("ModList"):ModList()
-		scaledList:ScaleAddList(modList, scale)
-		modList = scaledList
+	if hasScale then
+		local scale = calcLib.mod(modList, nil, "PassiveSkillEffect")
+		if scale ~= 1 then
+			local scaledList = new("ModList"):ModList()
+			scaledList:ScaleAddList(modList, scale)
+			modList = scaledList
+		end
 	end
 
 	-- Run second pass radius jewels
-	for _, rad in pairs(env.radiusJewelList) do
+	local rescan = false
+	for i = 1, #env.radiusJewelList do
+		local rad = env.radiusJewelList[i]
 		if rad.nodes[node.id] and rad.nodes[node.id].type ~= "Mastery" and (rad.type == "Threshold" or (rad.type == "Self" and env.allocNodes[node.id]) or (rad.type == "SelfUnalloc" and not env.allocNodes[node.id])) then
 			rad.func(node, modList, rad.data)
+			rescan = true
+			hasOtherEffect = nil
+			hasExtraSkill = nil
+			hasExplode = nil
+		end
+	end
+
+	if rescan then
+		for i = 1, #modList do
+			local name = modList[i].name
+			if name == "PassiveSkillHasOtherEffect" then
+				hasOtherEffect = true
+			elseif name == "ExtraSkill" then
+				hasExtraSkill = true
+			elseif name == "CanExplode" then
+				hasExplode = true
+			end
 		end
 	end
 
-	if modList:Flag(nil, "PassiveSkillHasOtherEffect") then
-		for i, mod in ipairs(modList:List(skillCfg, "NodeModifier")) do
-			if i == 1 then wipeTable(modList) end
-			modList:AddMod(mod.mod)
+	if hasOtherEffect and modList:Flag(nil, "PassiveSkillHasOtherEffect") then
+		local newMods = modList:List(nil, "NodeModifier")
+		for i = 1, #newMods do
+			local mod = newMods[i].mod
+			if i == 1 then
+				wipeTable(modList)
+				hasExtraSkill = nil
+				hasExplode = nil
+			end
+			if mod.name == "ExtraSkill" then
+				hasExtraSkill = true
+			elseif mod.name == "CanExplode" then
+				hasExplode = true
+			end
+			modList:AddMod(mod)
 		end
 	end
 
-	node.grantedSkills = { }
-	for _, skill in ipairs(modList:List(nil, "ExtraSkill")) do
-		if skill.name ~= "Unknown" then
-			t_insert(node.grantedSkills, {
-				skillId = skill.skillId,
-				level = skill.level,
-				noSupports = true,
-				source = "Tree:"..node.id
-			})
+	node.grantedSkills = wipeTable(node.grantedSkills)
+	if hasExtraSkill then
+		local list = modList:List(nil, "ExtraSkill")
+		for i = 1, #list do
+			local skill = list[i]
+			if skill.name ~= "Unknown" then
+				t_insert(node.grantedSkills, {
+					skillId = skill.skillId,
+					level = skill.level,
+					noSupports = true,
+					source = "Tree:" .. node.id
+				})
+			end
 		end
 	end
 
-	return modList, modList:Flag(nil, "CanExplode") and node
+	if hasExplode then
+		return modList, modList:Flag(nil, "CanExplode") and node
+	else
+		return modList
+	end
 end
 
 -- Build list of modifiers from the listed tree nodes
@@ -181,8 +261,12 @@ function calcs.buildModListForNodeList(env, nodeList, finishJewels)
 	-- Add node modifiers
 	local modList = new("ModList"):ModList()
 	local explodeSources = {}
+	-- Outside MAIN mode the per-node list is merged into modList and then
+	-- dropped, so a single list can be recycled for every node instead of
+	-- allocating one each time.
+	local scratch = env.mode ~= "MAIN" and new("ModList"):ModList() or nil
 	for _, node in pairs(nodeList) do
-		local nodeModList, explode = calcs.buildModListForNode(env, node)
+		local nodeModList, explode = calcs.buildModListForNode(env, node, scratch)
 		t_insert(explodeSources, explode)
 		modList:AddList(nodeModList)
 		if env.mode == "MAIN" then
@@ -193,7 +277,7 @@ function calcs.buildModListForNodeList(env, nodeList, finishJewels)
 	if finishJewels then
 		-- Process extra radius nodes; these are unallocated nodes near conversion or threshold jewels that need to be processed
 		for _, node in pairs(env.extraRadiusNodeList) do
-			local nodeModList = calcs.buildModListForNode(env, node)
+			local nodeModList = calcs.buildModListForNode(env, node, scratch)
 			if env.mode == "MAIN" then
 				node.finalModList = nodeModList
 			end
diff --git a/src/Modules/Common.lua b/src/Modules/Common.lua
index 20e3346330..d9f7115282 100644
--- a/src/Modules/Common.lua
+++ b/src/Modules/Common.lua
@@ -76,6 +76,25 @@ local function getClass(className)
 	return class
 end
 
+-- wrap constructor to check that the constructors for all parent and superparent classes have been called
+local function wrapConstructor(class, className, originalFunc)
+	return function(self, ...)
+		local ret = originalFunc(self, ...)
+		if class._parents then
+			for parent in pairs(class._superParents) do
+				if parent[parent._className] and not self._parentInit[parent] then
+					error("Parent class '" ..
+						parent._className .. "' of class '" .. className .. "' must be initialised")
+				end
+			end
+		end
+		if not ret then
+			error(string.format("Class %s constructor did not return a value", className))
+		end
+		return ret
+	end
+end
+
 ---@generic T
 ---@param className `T`
 ---@param ... string parent class names
@@ -90,8 +109,11 @@ function newClass(className, ...)
 		end
 		return obj
 	end
+	-- a list of metatables. one for each parent
+	class._metaList = {}
 	class._className = className
 	local numVarArg = select("#", ...)
+	local parentIndex
 	if numVarArg > 0 then
 		-- Build list of parent classes
 		class._parents = { }
@@ -102,21 +124,79 @@ function newClass(className, ...)
 		class._superParents = { }
 		addSuperParents(class, class)
 		-- Set up inheritance
-		setmetatable(class, {
-			__index = function(self, key)
-				for _, parent in ipairs(class._parents) do
-					local val = parent[key]
-					if val ~= nil then
-						self[key] = val
-						return val
-					end
+		function parentIndex(self, key)
+			for _, parent in ipairs(class._parents) do
+				local val = parent[key]
+				if val ~= nil then
+					rawset(self, key, val)
+					return val
 				end
 			end
-		})
+		end
 	end
+	setmetatable(class, {
+		__index = parentIndex,
+		__newindex = function(self, k, v)
+			if k == className then
+				-- Check that the constructors for all parent and superparent classes have been called
+				v = wrapConstructor(class, className, v)
+			end
+			rawset(self, k, v)
+		end
+	})
+	class._unconstructedMeta = {
+		__index = function(obj, key)
+			if key == className then
+				setmetatable(obj, class)
+				return class[className]
+			end
+			error(s_format(
+				"Object of class '%s' was used before it was constructed (accessed '%s'). Did you forget to call new(\"%s\"):%s()?",
+				className, tostring(key), className, className))
+		end,
+	}
 	return class
 end
 
+-- avoid rebuilding metatables constantly. this is done by caching class-parent pair metatables
+local function getMeta(class, parent)
+	local metaList = rawget(class, "_metaList")
+	local meta = metaList[parent]
+	if not meta then
+		local parentName = parent._className
+		meta = {
+			__index = function(proxy, key)
+				local object = rawget(proxy, "_object")
+				local v = rawget(object, key)
+				if v ~= nil then
+					return v
+				else
+					return parent[key]
+				end
+			end,
+			__newindex = function(proxy, k, v)
+				local object = rawget(proxy, "_object")
+				object[k] = v
+			end,
+			__call = function(proxy, self, ...)
+				local object = rawget(proxy, "_object")
+				if not parent[parentName] then
+					error("Parent class '" .. parentName .. "' of class '" .. class._className .. "' has no constructor")
+				end
+				if object._parentInit[parent] then
+					error("Parent class '" .. parentName .. "' of class '" .. class._className .. "' has already been initialised")
+				end
+				if self ~= object then
+					error(string.format("Parent class %s constructor of class %s was not provided self. Are you perhaps calling it with self.%s instead of self:%s?", parentName, class._className, parentName, parentName))
+				end
+				parent[parent._className](self, ...)
+				object._parentInit[parent] = true
+			end,
+		}
+		metaList[parent] = meta
+	end
+	return meta
+end
 ---@generic T
 ---@param className `T`
 ---@param extraArg nil Never pass extra parameters. Defined purely to guard against old syntax.
@@ -130,77 +210,14 @@ function new(className, extraArg)
 	end
 	local class = getClass(className)
 	-- protect against calling new("Foo") without calling :Foo()
-	local object
-	if class[className] then
-		if not rawget(class, "_unconstructedMeta") then
-			class._unconstructedMeta = {
-				__index = function(obj, key)
-					if key == className then
-						setmetatable(obj, class)
-						return class[className]
-					end
-					error(s_format(
-						"Object of class '%s' was used before it was constructed (accessed '%s'). Did you forget to call new(\"%s\"):%s()?",
-						className, tostring(key), className, className))
-				end,
-			}
-		end
-		object = setmetatable({}, class._unconstructedMeta)
-	else
-		object = setmetatable({}, class)
-	end
+	local object = setmetatable({}, class._unconstructedMeta or class)
 	object.Object = object
 	if class._parents then
 		-- Add parent and superparent class proxies
 		object._parentInit = { }
 		for parent in pairs(class._superParents) do
-			local proxyMeta = {
-				__index = function(self, key)
-					local v = rawget(object, key)
-					if v ~= nil then
-						return v
-					else
-						return parent[key]
-					end
-				end,
-				__newindex = object,
-				__call = function(_, self, ...)
-					if not parent[parent._className] then
-						error("Parent class '"..parent._className.."' of class '"..class._className.."' has no constructor")
-					end
-					if object._parentInit[parent] then
-						error("Parent class '"..parent._className.."' of class '"..class._className.."' has already been initialised")
-					end
-					if self ~= object then
-						error(string.format("Parent class %s constructor of class %s was not provided self. Are you perhaps calling it with self.%s instead of self:%s?", parent._className, className, parent._className, parent._className))
-					end
-					parent[parent._className](self, ...)
-					object._parentInit[parent] = true
-				end,
-			}
-			object[parent._className] = setmetatable(proxyMeta, proxyMeta)
-		end
-	end
-
-	if class[className] and not rawget(class, "_constructorInitialised") then
-		local originalFunc = class[className]
-		class[className] = function(self, ...)
-			local ret = originalFunc(self, ...)
-			if class._parents then
-				-- Check that the constructors for all parent and superparent classes have been called
-				for parent in pairs(class._superParents) do
-					if parent[parent._className] and not self._parentInit[parent] then
-						error("Parent class '" ..
-							parent._className .. "' of class '" .. className .. "' must be initialised")
-					end
-				end
-			end
-			if not ret then
-				error(string.format("Class %s constructor did not return a value", className))
-			end
-			return ret
+			object[parent._className] = setmetatable({ _object = object }, getMeta(class, parent))
 		end
-		class._constructorInitialised = true
 	end
 	return object
 end