diff --git a/keymap/CHANGELOG.md b/keymap/CHANGELOG.md
new file mode 100644
index 0000000..13fa7e4
--- /dev/null
+++ b/keymap/CHANGELOG.md
@@ -0,0 +1,21 @@
+# Changelog
+
+All notable changes to Keymap are documented in this file.
+
+## [1.3.1] - 2026-07-21
+
+### Fixed
+
+- Prevented startup timeouts while parsing larger Niri, Hyprland, and MangoWC configurations.
+- Prevented intermittent callback timeouts when rapidly switching keyboard modifier layers.
+
+### Changed
+
+- Accelerated stable fingerprints with Luau's native `bit32` operations while retaining a plain-Lua fallback.
+- Avoided reading Niri's root configuration twice during a refresh.
+- Made loading snapshots lightweight instead of serializing the previous bind tree again.
+- Cached panel translations, settings, keyboard indexes, colors, and dynamic key callbacks between renders.
+
+### Tests
+
+- Added 93-bind scale regressions for Niri, Hyprland, and MangoWC.
diff --git a/keymap/mangowc_service.luau b/keymap/mangowc_service.luau
index 867619b..eaa7134 100644
--- a/keymap/mangowc_service.luau
+++ b/keymap/mangowc_service.luau
@@ -442,35 +442,30 @@ end
 
 -- FNV-1a over the exact source line. The editor recalculates this before a
 -- write so a bind is never replaced after the file changed behind its back.
--- Multiplication is split into 16-bit words to retain exact 32-bit arithmetic
--- in runtimes where Lua numbers are doubles.
-local function xorLowByte(value, byte)
-	local low = value % 256
+-- Splitting the prime into 2^24 + 403 retains exact 32-bit arithmetic in
+-- runtimes where Lua numbers are doubles.
+local function xorByte(left, right)
 	local result = 0
 	local place = 1
 	for _ = 1, 8 do
-		if low % 2 ~= byte % 2 then
+		if left % 2 ~= right % 2 then
 			result = result + place
 		end
-		low = math.floor(low / 2)
-		byte = math.floor(byte / 2)
+		left = math.floor(left / 2)
+		right = math.floor(right / 2)
 		place = place * 2
 	end
-	return value - (value % 256) + result
+	return result
 end
 
+local xorByteFast = type(bit32) == "table" and type(bit32.bxor) == "function" and bit32.bxor or xorByte
+
 fingerprint = function(rawSnippet)
 	local hash = 2166136261
 	for index = 1, #rawSnippet do
-		hash = xorLowByte(hash, rawSnippet:byte(index))
-		local low = hash % 65536
-		local high = math.floor(hash / 65536)
-		local lowProduct = low * 403
-		local resultLow = lowProduct % 65536
-		local resultHigh = (
-			math.floor(lowProduct / 65536) + low * 256 + high * 403
-		) % 65536
-		hash = resultHigh * 65536 + resultLow
+		local low = hash % 256
+		hash = hash - low + xorByteFast(low, rawSnippet:byte(index))
+		hash = (hash * 403 + (hash % 256) * 16777216) % 4294967296
 	end
 	return string.format("%08x", hash)
 end
@@ -918,15 +913,11 @@ function refresh()
 	refreshing = true
 
 	local source = configPath()
-	local previous = noctalia.state.get(SNAPSHOT_KEY)
-	local sameCompositor = type(previous) == "table" and previous.compositor == "MangoWC"
-	local previousCategories = sameCompositor and previous.categories or {}
-	local previousTotal = sameCompositor and previous.total or 0
-	local previousUpdatedAt = sameCompositor and previous.updated_at or ""
-	local previousHidden = sameCompositor and previous.hidden or {}
+	-- The panel keeps its last ready snapshot while this status is loading.
+	-- Avoid serializing the complete bind tree a second time on every refresh.
 	noctalia.state.set(
 		SNAPSHOT_KEY,
-		snapshot("loading", source, "", previousCategories, previousTotal, {}, previousUpdatedAt, previousHidden)
+		snapshot("loading", source, "", {}, 0, {}, "", {})
 	)
 
 	local parsed = parseConfig(source)
diff --git a/keymap/niri_service.luau b/keymap/niri_service.luau
index 1c860d9..f59ff07 100644
--- a/keymap/niri_service.luau
+++ b/keymap/niri_service.luau
@@ -452,14 +452,17 @@ local function xorByte(left, right)
 	return result
 end
 
--- FNV-1a 32-bit without bit libraries. Splitting the prime (0x01000193) into
--- 2^24 + 403 keeps every intermediate below the exact integer limit of a
--- Lua/Luau number.
+local xorByteFast = type(bit32) == "table" and type(bit32.bxor) == "function" and bit32.bxor or xorByte
+
+-- Splitting the FNV prime (0x01000193) into 2^24 + 403 keeps every
+-- intermediate below the exact integer limit of a Lua/Luau number. Luau's
+-- native bit32 fast path avoids eight interpreted operations for every byte;
+-- the arithmetic fallback keeps the parser usable in plain-Lua tests.
 local function stableFingerprint(value)
 	local hash = 2166136261
 	for index = 1, #value do
 		local low = hash % 256
-		hash = hash - low + xorByte(low, value:byte(index))
+		hash = hash - low + xorByteFast(low, value:byte(index))
 		hash = (hash * 403 + (hash % 256) * 16777216) % 4294967296
 	end
 	return string.format("%08x", hash)
@@ -688,7 +691,7 @@ local function parseBind(combo, attributes, action, category, records, activeByC
 	activeByCombo[signature] = bind
 end
 
-local function parseConfig(root)
+local function parseConfig(root, rootSource)
 	local records = {}
 	local hidden = {}
 	local activeByCombo = {}
@@ -706,7 +709,7 @@ local function parseConfig(root)
 	end
 
 	local parseFile
-	parseFile = function(path, optional)
+	parseFile = function(path, optional, providedSource)
 		if visiting[path] then
 			warn("niri_include_cycle:" .. path)
 			return
@@ -715,7 +718,7 @@ local function parseConfig(root)
 			warn("niri_file_limit_reached")
 			return
 		end
-		local source = noctalia.readFile(path)
+		local source = providedSource or noctalia.readFile(path)
 		if type(source) ~= "string" then
 			warn((optional and "niri_optional_include_missing:" or "niri_include_unreadable:") .. path)
 			if not optional then
@@ -858,7 +861,7 @@ local function parseConfig(root)
 		visiting[path] = nil
 	end
 
-	parseFile(root, false)
+	parseFile(root, false, rootSource)
 	local categories, total = buildCategories(records)
 	return categories, total, hidden, warnings, fatalError
 end
@@ -897,18 +900,16 @@ function refresh()
 	end
 	refreshing = true
 	local source = sourcePath()
-	local previous = noctalia.state.get(SNAPSHOT_KEY)
-	local keepPrevious = type(previous) == "table" and previous.compositor == "Niri"
-	local previousCategories = keepPrevious and previous.categories or {}
-	local previousTotal = keepPrevious and previous.total or 0
-	local previousUpdatedAt = keepPrevious and previous.updated_at or ""
-	local previousHidden = keepPrevious and previous.hidden or {}
+	-- The panel keeps its last ready snapshot while this status is loading.
+	-- Do not copy the full bind tree through the shared-state serializer merely
+	-- to replace it again at the end of this synchronous refresh.
 	noctalia.state.set(
 		SNAPSHOT_KEY,
-		snapshot("loading", source, "", previousCategories, previousTotal, {}, previousUpdatedAt, previousHidden)
+		snapshot("loading", source, "", {}, 0, {}, "", {})
 	)
 
-	if type(noctalia.readFile(source)) ~= "string" then
+	local rootSource = noctalia.readFile(source)
+	if type(rootSource) ~= "string" then
 		noctalia.state.set(
 			SNAPSHOT_KEY,
 			snapshot("error", source, "niri_config_unreadable", {}, 0, {}, os.date("%H:%M:%S"))
@@ -917,7 +918,7 @@ function refresh()
 		return
 	end
 
-	local categories, total, hidden, warnings, fatalError = parseConfig(source)
+	local categories, total, hidden, warnings, fatalError = parseConfig(source, rootSource)
 	if fatalError ~= nil then
 		noctalia.state.set(
 			SNAPSHOT_KEY,
diff --git a/keymap/panel.luau b/keymap/panel.luau
index 837264e..677c254 100644
--- a/keymap/panel.luau
+++ b/keymap/panel.luau
@@ -112,12 +112,36 @@ do
   end
 end
 
+local NIL_CACHE_VALUE = {}
+local configCache = {}
+local translationCache = {}
+
 local function tr(key, args)
-  return noctalia.tr(key, args)
+  if args ~= nil then
+    return noctalia.tr(key, args)
+  end
+  local cached = translationCache[key]
+  if cached ~= nil then
+    return cached
+  end
+  local value = noctalia.tr(key)
+  translationCache[key] = value
+  return value
 end
 
 local function cfg(key)
-  return noctalia.getConfig(key)
+  local cached = configCache[key]
+  if cached ~= nil then
+    return cached ~= NIL_CACHE_VALUE and cached or nil
+  end
+  local value = noctalia.getConfig(key)
+  configCache[key] = value ~= nil and value or NIL_CACHE_VALUE
+  return value
+end
+
+local function clearHostValueCaches()
+  configCache = {}
+  translationCache = {}
 end
 
 local function asString(value, fallback)
@@ -297,7 +321,13 @@ local function expandedKeys(value)
   return { canonical }
 end
 
+local keyboardIndexSnapshot = nil
+local keyboardIndexCache = nil
+
 local function keyboardIndex()
+  if keyboardIndexSnapshot == snapshot and keyboardIndexCache ~= nil then
+    return keyboardIndexCache
+  end
   local exact = {}
   local any = {}
   for _, category in ipairs(asArray(snapshot.categories)) do
@@ -318,14 +348,20 @@ local function keyboardIndex()
       end
     end
   end
-  return { exact = exact, any = any }
+  keyboardIndexSnapshot = snapshot
+  keyboardIndexCache = { exact = exact, any = any }
+  return keyboardIndexCache
 end
 
+local keyCallbackCache = {}
 local function keyCallback(id, code)
   local name = "onKeyboardKey_" .. id
-  return registerDynamicCallback(name, function()
-    selectKeyboardKey(code)
-  end)
+  local callback = keyCallbackCache[name]
+  if callback == nil then
+    callback = function() selectKeyboardKey(code) end
+    keyCallbackCache[name] = callback
+  end
+  return registerDynamicCallback(name, callback)
 end
 
 local function contains(haystack, needle)
@@ -848,21 +884,32 @@ local function keyboardUnitsWidth(units)
   return math.max(1, math.floor(value * KEYBOARD_UNIT + (value - 1) * KEYBOARD_GAP + 0.5))
 end
 
+local colorWithOpacityCache = {}
 local function colorWithOpacity(value, fallback, opacity)
+  local cacheKey = asString(value) .. "\0" .. asString(fallback) .. "\0" .. tostring(opacity)
+  local cached = colorWithOpacityCache[cacheKey]
+  if cached ~= nil then return cached end
   local color = asString(value, fallback)
+  local result
   if string.sub(color, 1, 1) == "#" then
     local alpha = string.format("%02X", math.floor(math.max(0, math.min(1, opacity)) * 255 + 0.5))
     if #color == 7 then
-      return color .. alpha
+      result = color .. alpha
     elseif #color == 9 then
-      return string.sub(color, 1, 7) .. alpha
+      result = string.sub(color, 1, 7) .. alpha
+    else
+      result = color
     end
-    return color
+  else
+    result = color .. "/" .. string.format("%.2f", opacity)
   end
-  return color .. "/" .. string.format("%.2f", opacity)
+  colorWithOpacityCache[cacheKey] = result
+  return result
 end
 
-local function keyboardKeyNode(spec, index)
+local EMPTY_ENTRIES = {}
+
+local function keyboardKeyNode(spec, index, signature)
   if spec.spacer ~= nil then
     -- `ui.spacer` is flexible: inside a fixed-width row it absorbs remaining
     -- space and moves every key that follows it. Keyboard gaps must be rigid,
@@ -892,9 +939,8 @@ local function keyboardKeyNode(spec, index)
   end
 
   local code = canonicalKey(spec.code)
-  local signature = activeModifierSignature()
-  local exactEntries = asArray(index.exact[signature .. "|" .. code])
-  local anyEntries = asArray(index.any[code])
+  local exactEntries = index.exact[signature .. "|" .. code] or EMPTY_ENTRIES
+  local anyEntries = index.any[code] or EMPTY_ENTRIES
   local physicalModifier = MODIFIER_ALIASES[normalized(spec.code)]
   local modifierActive = physicalModifier ~= nil and activeModifiers[physicalModifier] == true
   local selected = creatorOpen and creatorHasKey(code) or selectedKeyboardKey == code
@@ -1571,7 +1617,7 @@ local function keyboardBody()
   for rowIndex, row in ipairs(layout.rows) do
     local keys = {}
     for _, spec in ipairs(row) do
-      keys[#keys + 1] = keyboardKeyNode(spec, index)
+      keys[#keys + 1] = keyboardKeyNode(spec, index, signature)
     end
     keyboardRows[#keyboardRows + 1] = ui.row({
       key = "keyboard-row-" .. layout.id .. "-" .. tostring(rowIndex),
@@ -2627,7 +2673,7 @@ end
 render = function()
   renderCallbackNames = {}
   local status = asString(snapshot.status, "idle")
-  local categories = filteredCategories()
+  local categories = viewMode == "list" and filteredCategories() or EMPTY_ENTRIES
   local requestedColumns = math.max(1, math.min(4, math.floor(tonumber(cfg("columns")) or 3)))
   local body
   if status == "error" then
@@ -2728,6 +2774,7 @@ noctalia.state.watch(UPDATE_RESULT_KEY, function(result)
 end)
 
 function onOpen(_context)
+  clearHostValueCaches()
   local configuredLayout = asString(cfg("keyboard_layout"), "100")
   keyboardLayoutId = KEYBOARD_LAYOUTS[configuredLayout] ~= nil and configuredLayout or "100"
   local current = noctalia.state.get(SNAPSHOT_KEY)
@@ -2755,6 +2802,7 @@ function onOpen(_context)
 end
 
 function onConfigChanged()
+  clearHostValueCaches()
   render()
 end
 
diff --git a/keymap/plugin.toml b/keymap/plugin.toml
index aad8572..b2fe007 100644
--- a/keymap/plugin.toml
+++ b/keymap/plugin.toml
@@ -1,6 +1,6 @@
 id = "blackbartblues/keymap"
 name = "Keymap"
-version = "1.3.0"
+version = "1.3.1"
 plugin_api = 5
 author = "blackbartblues"
 license = "MIT"
diff --git a/keymap/service.luau b/keymap/service.luau
index 3ba0c7f..72299fc 100644
--- a/keymap/service.luau
+++ b/keymap/service.luau
@@ -314,11 +314,13 @@ local function xorByte(left, right)
 	return result
 end
 
+local xorByteFast = type(bit32) == "table" and type(bit32.bxor) == "function" and bit32.bxor or xorByte
+
 local function fingerprint(value)
 	local hash = 2166136261
 	for index = 1, #value do
 		local low = hash % 256
-		hash = hash - low + xorByte(low, value:byte(index))
+		hash = hash - low + xorByteFast(low, value:byte(index))
 		hash = (hash * 403 + (hash % 256) * 16777216) % 4294967296
 	end
 	return string.format("%08x", hash)
@@ -1003,14 +1005,11 @@ function refresh()
 	refreshing = true
 
 	local source = expandedConfigPath()
-	local previous = noctalia.state.get(SNAPSHOT_KEY)
-	local previousCategories = type(previous) == "table" and previous.categories or {}
-	local previousTotal = type(previous) == "table" and previous.total or 0
-	local previousUpdatedAt = type(previous) == "table" and previous.updated_at or ""
-	local previousHidden = type(previous) == "table" and previous.hidden or {}
+	-- The panel keeps its last ready snapshot while this status is loading.
+	-- Avoid serializing the complete bind tree a second time on every refresh.
 	noctalia.state.set(
 		SNAPSHOT_KEY,
-		snapshot("loading", source, "", previousCategories, previousTotal, {}, previousUpdatedAt, previousHidden)
+		snapshot("loading", source, "", {}, 0, {}, "", {})
 	)
 
 	if not noctalia.commandExists("hyprctl") then
diff --git a/keymap/tests/hypr_scale_test.lua b/keymap/tests/hypr_scale_test.lua
new file mode 100644
index 0000000..a4a1bc9
--- /dev/null
+++ b/keymap/tests/hypr_scale_test.lua
@@ -0,0 +1,87 @@
+local sourceLines = {}
+local liveBinds = {}
+for index = 1, 93 do
+  if index % 20 == 1 then
+    sourceLines[#sourceLines + 1] = "-- " .. tostring(math.floor(index / 20) + 1) .. ". Group "
+      .. tostring(math.floor(index / 20) + 1)
+  end
+  sourceLines[#sourceLines + 1] = string.format(
+    'hl.bind("SUPER+Key%d", action, { description = "Action %d" })', index, index
+  )
+  liveBinds[#liveBinds + 1] = {
+    modmask = 64, key = "Key" .. tostring(index), description = "Action " .. tostring(index),
+    has_description = true, dispatcher = "__lua", arg = tostring(index), submap = "",
+  }
+end
+local source = table.concat(sourceLines, "\n")
+
+local values, watchers = {
+  ["keymap.snapshot"] = {
+    status = "ready", compositor = "Hyprland", total = 1,
+    categories = { { name = "Previous", binds = { { id = "previous" } } } },
+  },
+}, {}
+local reads, xorCalls, loadingCategoryCount = 0, 0, -1
+local originalBit32 = bit32
+bit32 = {
+  bxor = function(left, right)
+    xorCalls = xorCalls + 1
+    local result, place = 0, 1
+    for _ = 1, 8 do
+      if left % 2 ~= right % 2 then result = result + place end
+      left = math.floor(left / 2)
+      right = math.floor(right / 2)
+      place = place * 2
+    end
+    return result
+  end,
+}
+
+noctalia = {
+  state = {
+    get = function(key) return values[key] end,
+    set = function(key, value)
+      if key == "keymap.snapshot" and value.status == "loading" then
+        loadingCategoryCount = #(value.categories or {})
+      end
+      values[key] = value
+      if watchers[key] ~= nil then watchers[key](value) end
+    end,
+    watch = function(key, callback) watchers[key] = callback end,
+  },
+  getConfig = function(key)
+    return ({
+      compositor = "hyprland", hyprland_config = "/fixture/hyprland.lua",
+      merge_sequential = false, show_undescribed = true,
+    })[key]
+  end,
+  getenv = function(key) return key == "HYPRLAND_INSTANCE_SIGNATURE" and "test" or "" end,
+  expandPath = function(path) return path end,
+  fileExists = function(path) return path == "/fixture/hyprland.lua" end,
+  listDir = function() return nil end,
+  readFile = function(path)
+    if path ~= "/fixture/hyprland.lua" then return nil end
+    reads = reads + 1
+    return source
+  end,
+  commandExists = function(command) return command == "hyprctl" end,
+  json = { decode = function() return liveBinds end },
+  runAsync = function(command, callback)
+    callback({ exitCode = 0, timedOut = false, stdout = "fixture" })
+    return true
+  end,
+  tr = function(key) return key == "category.other" and "Other" or key end,
+}
+
+assert(loadfile("service.luau"))()
+bit32 = originalBit32
+
+local snapshot = values["keymap.snapshot"]
+assert(snapshot.status == "ready", "large Hyprland fixture did not parse")
+assert(snapshot.total == 93, "large Hyprland fixture lost binds")
+assert(#snapshot.categories == 5, "large Hyprland fixture lost category markers")
+assert(reads == 1, "Hyprland root config should only be read once per refresh")
+assert(loadingCategoryCount == 0, "loading snapshot should not reserialize the previous bind tree")
+assert(xorCalls > 0, "Hyprland parser did not use the native-xor fingerprint path")
+
+print("hypr scale tests: ok")
diff --git a/keymap/tests/mangowc_scale_test.lua b/keymap/tests/mangowc_scale_test.lua
new file mode 100644
index 0000000..7478586
--- /dev/null
+++ b/keymap/tests/mangowc_scale_test.lua
@@ -0,0 +1,75 @@
+local sourceLines = {}
+for index = 1, 93 do
+  if index % 20 == 1 then
+    sourceLines[#sourceLines + 1] = "# Group " .. tostring(math.floor(index / 20) + 1)
+  end
+  sourceLines[#sourceLines + 1] = string.format(
+    'bind=SUPER,Key%d,spawn_shell,true #"Action %d"', index, index
+  )
+end
+local source = table.concat(sourceLines, "\n")
+
+local values, watchers = {
+  ["keymap.snapshot"] = {
+    status = "ready", compositor = "MangoWC", total = 1,
+    categories = { { name = "Previous", binds = { { id = "previous" } } } },
+  },
+}, {}
+local reads, xorCalls, loadingCategoryCount = 0, 0, -1
+local originalBit32 = bit32
+bit32 = {
+  bxor = function(left, right)
+    xorCalls = xorCalls + 1
+    local result, place = 0, 1
+    for _ = 1, 8 do
+      if left % 2 ~= right % 2 then result = result + place end
+      left = math.floor(left / 2)
+      right = math.floor(right / 2)
+      place = place * 2
+    end
+    return result
+  end,
+}
+
+noctalia = {
+  state = {
+    get = function(key) return values[key] end,
+    set = function(key, value)
+      if key == "keymap.snapshot" and value.status == "loading" then
+        loadingCategoryCount = #(value.categories or {})
+      end
+      values[key] = value
+      if watchers[key] ~= nil then watchers[key](value) end
+    end,
+    watch = function(key, callback) watchers[key] = callback end,
+  },
+  getConfig = function(key)
+    return ({ compositor = "mangowc", mangowc_config = "/fixture/config.conf", merge_sequential = false })[key]
+  end,
+  getenv = function(key) return key == "MANGO_INSTANCE_SIGNATURE" and "test" or "" end,
+  expandPath = function(path) return path end,
+  fileExists = function(path) return path == "/fixture/config.conf" end,
+  listDir = function() return nil end,
+  readFile = function(path)
+    if path ~= "/fixture/config.conf" then return nil end
+    reads = reads + 1
+    return source
+  end,
+  tr = function(key, args)
+    if args ~= nil and args.action ~= nil then return args.action end
+    return key == "category.other" and "Other" or key
+  end,
+}
+
+assert(loadfile("mangowc_service.luau"))()
+bit32 = originalBit32
+
+local snapshot = values["keymap.snapshot"]
+assert(snapshot.status == "ready", "large MangoWC fixture did not parse")
+assert(snapshot.total == 93, "large MangoWC fixture lost binds")
+assert(#snapshot.categories == 5, "large MangoWC fixture lost category markers")
+assert(reads == 1, "MangoWC root config should only be read once per refresh")
+assert(loadingCategoryCount == 0, "loading snapshot should not reserialize the previous bind tree")
+assert(xorCalls > 0, "MangoWC parser did not use the native-xor fingerprint path")
+
+print("MangoWC scale tests: ok")
diff --git a/keymap/tests/niri_scale_test.lua b/keymap/tests/niri_scale_test.lua
new file mode 100644
index 0000000..69a9299
--- /dev/null
+++ b/keymap/tests/niri_scale_test.lua
@@ -0,0 +1,84 @@
+local bindLines = { "binds {" }
+for index = 1, 93 do
+  if index % 20 == 1 then
+    bindLines[#bindLines + 1] = '    // #"Group ' .. tostring(math.floor(index / 20) + 1) .. '"'
+  end
+  bindLines[#bindLines + 1] = string.format(
+    '    Mod+Key%d repeat=false cooldown-ms=150 { focus-workspace %d; }', index, index
+  )
+end
+bindLines[#bindLines + 1] = "}"
+local source = table.concat(bindLines, "\n")
+
+local values, watchers = {
+  ["keymap.snapshot"] = {
+    status = "ready", compositor = "Niri", total = 1,
+    categories = { { name = "Previous", binds = { { id = "previous" } } } },
+  },
+}, {}
+local reads = 0
+local xorCalls = 0
+local loadingCategoryCount = -1
+local originalBit32 = bit32
+bit32 = {
+  bxor = function(left, right)
+    xorCalls = xorCalls + 1
+    local result, place = 0, 1
+    for _ = 1, 8 do
+      if left % 2 ~= right % 2 then result = result + place end
+      left = math.floor(left / 2)
+      right = math.floor(right / 2)
+      place = place * 2
+    end
+    return result
+  end,
+}
+
+noctalia = {
+  state = {
+    get = function(key) return values[key] end,
+    set = function(key, value)
+      if key == "keymap.snapshot" and value.status == "loading" then
+        loadingCategoryCount = #(value.categories or {})
+      end
+      values[key] = value
+      if watchers[key] ~= nil then watchers[key](value) end
+    end,
+    watch = function(key, callback) watchers[key] = callback end,
+  },
+  getConfig = function(key)
+    return ({ compositor = "niri", niri_config = "/fixture/config.kdl", merge_sequential = false })[key]
+  end,
+  getenv = function(key) return key == "NIRI_SOCKET" and "test" or "" end,
+  fileExists = function(path) return path == "/fixture/config.kdl" end,
+  listDir = function() return nil end,
+  readFile = function(path)
+    if path ~= "/fixture/config.kdl" then return nil end
+    reads = reads + 1
+    return source
+  end,
+  tr = function(key, args)
+    if args ~= nil and args.action ~= nil then return args.action end
+    return key == "category.other" and "Other" or key
+  end,
+}
+
+assert(loadfile("niri_service.luau"))()
+bit32 = originalBit32
+
+local snapshot = values["keymap.snapshot"]
+assert(snapshot.status == "ready", "large Niri fixture did not parse")
+assert(snapshot.total == 93, "large Niri fixture lost binds")
+assert(#snapshot.categories == 5, "large Niri fixture lost category markers")
+assert(reads == 1, "Niri root config should only be read once per refresh")
+assert(loadingCategoryCount == 0, "loading snapshot should not reserialize the previous bind tree")
+assert(xorCalls > 0, "Niri parser did not use the native-xor fingerprint path")
+
+for _, category in ipairs(snapshot.categories) do
+  for _, bind in ipairs(category.binds) do
+    assert(bind.id:match("^niri:[0-9a-f]+$"), "invalid bind fingerprint")
+    assert(bind.fingerprint:match("^[0-9a-f]+$"), "invalid source fingerprint")
+  end
+end
+
+print("niri scale tests: ok")
diff --git a/keymap/writer_service.luau b/keymap/writer_service.luau
index 675f121..35c25ea 100644
--- a/keymap/writer_service.luau
+++ b/keymap/writer_service.luau
@@ -756,21 +756,24 @@ processValidatedRequest = function(request)
 	verifyAndReload(request, transaction)
 end
 
-local function contentFingerprint(value)
-	local function xorByte(left, right)
-		local result, place = 0, 1
-		for _ = 1, 8 do
-			if left % 2 ~= right % 2 then result = result + place end
-			left = math.floor(left / 2)
-			right = math.floor(right / 2)
-			place = place * 2
-		end
-		return result
+local function xorByte(left, right)
+	local result, place = 0, 1
+	for _ = 1, 8 do
+		if left % 2 ~= right % 2 then result = result + place end
+		left = math.floor(left / 2)
+		right = math.floor(right / 2)
+		place = place * 2
 	end
+	return result
+end
+
+local xorByteFast = type(bit32) == "table" and type(bit32.bxor) == "function" and bit32.bxor or xorByte
+
+local function contentFingerprint(value)
 	local hash = 2166136261
 	for index = 1, #value do
 		local low = hash % 256
-		hash = hash - low + xorByte(low, value:byte(index))
+		hash = hash - low + xorByteFast(low, value:byte(index))
 		hash = (hash * 403 + (hash % 256) * 16777216) % 4294967296
 	end
 	return string.format("%08x", hash)