diff --git a/packages/ui/src/App.tsx b/packages/ui/src/App.tsx
index 4420af92..04e3394b 100644
--- a/packages/ui/src/App.tsx
+++ b/packages/ui/src/App.tsx
@@ -1,15 +1,12 @@
-import { Component, For, Show, createMemo, createEffect, createSignal, onMount, onCleanup } from "solid-js"
+import { Component, For, Show, Suspense, createMemo, createEffect, createSignal, lazy, onMount, onCleanup } from "solid-js"
 import { Dialog } from "@kobalte/core/dialog"
 import { Toaster } from "solid-toast"
 import useMediaQuery from "@suid/material/useMediaQuery"
 import { Minimize2 } from "lucide-solid"
 import AlertDialog from "./components/alert-dialog"
-import FolderSelectionView from "./components/folder-selection-view"
 import { showConfirmDialog } from "./stores/alerts"
 import InstanceTabs from "./components/instance-tabs"
-import InstanceDisconnectedModal from "./components/instance-disconnected-modal"
 import InstanceShell from "./components/instance/instance-shell2"
-import { SettingsScreen } from "./components/settings-screen"
 import { InstanceMetadataProvider } from "./lib/contexts/instance-metadata-context"
 import { initMarkdown } from "./lib/markdown"
 import { initGithubStars } from "./stores/github-stars"
@@ -54,10 +51,16 @@ import {
 } from "./stores/sessions"
 
 import { getInstanceSessionIndicatorStatus } from "./stores/session-status"
-import { openSettings } from "./stores/settings-screen"
+import { openSettings, settingsOpen } from "./stores/settings-screen"
 
 const log = getLogger("actions")
 
+const LazyFolderSelectionView = lazy(() => import("./components/folder-selection-view"))
+const LazyInstanceDisconnectedModal = lazy(() => import("./components/instance-disconnected-modal"))
+const LazySettingsScreen = lazy(() =>
+  import("./components/settings-screen").then((module) => ({ default: module.SettingsScreen })),
+)
+
 const App: Component = () => {
   const { isDark } = useTheme()
   const { t } = useI18n()
@@ -409,12 +412,16 @@ const App: Component = () => {
 
   return (
     <>
-      <InstanceDisconnectedModal
-        open={Boolean(disconnectedInstance())}
-        folder={disconnectedInstance()?.folder}
-        reason={disconnectedInstance()?.reason}
-        onClose={handleDisconnectedInstanceClose}
-      />
+      <Show when={Boolean(disconnectedInstance())}>
+        <Suspense fallback={null}>
+          <LazyInstanceDisconnectedModal
+            open={Boolean(disconnectedInstance())}
+            folder={disconnectedInstance()?.folder}
+            reason={disconnectedInstance()?.reason}
+            onClose={handleDisconnectedInstanceClose}
+          />
+        </Suspense>
+      </Show>
 
       <Dialog open={Boolean(launchError())} modal>
         <Dialog.Portal>
@@ -527,29 +534,37 @@ const App: Component = () => {
             </>
           }
         >
-          <FolderSelectionView
-            onSelectFolder={handleSelectFolder}
-            isLoading={isSelectingFolder()}
-          />
+          <Suspense fallback={<div class="flex-1 min-h-0" />}>
+            <LazyFolderSelectionView
+              onSelectFolder={handleSelectFolder}
+              isLoading={isSelectingFolder()}
+            />
+          </Suspense>
         </Show>
 
         <Show when={showFolderSelection()}>
           <div class="fixed inset-0 bg-black/50 z-50 flex items-center justify-center">
             <div class="w-full h-full relative">
-              <FolderSelectionView
-                onSelectFolder={handleSelectFolder}
-                isLoading={isSelectingFolder()}
-                onClose={() => {
-                  setShowFolderSelection(false)
-                  clearLaunchError()
-                }}
-              />
+              <Suspense fallback={<div class="w-full h-full" />}>
+                <LazyFolderSelectionView
+                  onSelectFolder={handleSelectFolder}
+                  isLoading={isSelectingFolder()}
+                  onClose={() => {
+                    setShowFolderSelection(false)
+                    clearLaunchError()
+                  }}
+                />
+              </Suspense>
             </div>
           </div>
         </Show>
- 
-        <SettingsScreen />
- 
+
+        <Show when={settingsOpen()}>
+          <Suspense fallback={null}>
+            <LazySettingsScreen />
+          </Suspense>
+        </Show>
+
         <AlertDialog />
 
         <Toaster
diff --git a/packages/ui/src/components/instance/instance-shell2.tsx b/packages/ui/src/components/instance/instance-shell2.tsx
index 84e55578..d8407b1f 100644
--- a/packages/ui/src/components/instance/instance-shell2.tsx
+++ b/packages/ui/src/components/instance/instance-shell2.tsx
@@ -1,9 +1,11 @@
 import {
   For,
   Show,
+  Suspense,
   createEffect,
   createMemo,
   createSignal,
+  lazy,
   onCleanup,
   onMount,
   type Accessor,
@@ -22,11 +24,7 @@ import { keyboardRegistry, type KeyboardShortcut } from "../../lib/keyboard-regi
 
 import { isOpen as isCommandPaletteOpen, hideCommandPalette, showCommandPalette } from "../../stores/command-palette"
 import Kbd from "../kbd"
-import InstanceWelcomeView from "../instance-welcome-view"
-import InfoView from "../info-view"
-import CommandPalette from "../command-palette"
 import PermissionNotificationBanner from "../permission-notification-banner"
-import PermissionApprovalModal from "../permission-approval-modal"
 import SessionView from "../session/session-view"
 import { formatTokenTotal } from "../../lib/formatters"
 import ContextMeter from "../context-meter"
@@ -34,7 +32,6 @@ import { sseManager } from "../../lib/sse-manager"
 import { getLogger } from "../../lib/logger"
 import { serverApi } from "../../lib/api-client"
 import { loadBackgroundProcesses } from "../../stores/background-processes"
-import { BackgroundProcessOutputDialog } from "../background-process-output-dialog"
 import { useI18n } from "../../lib/i18n"
 import { getPermissionQueueLength, getQuestionQueueLength } from "../../stores/instances"
 import SessionSidebar from "./shell/SessionSidebar"
@@ -60,6 +57,14 @@ import { useInstanceSessionContext } from "./shell/useInstanceSessionContext"
 
 const log = getLogger("session")
 
+const LazyInstanceWelcomeView = lazy(() => import("../instance-welcome-view"))
+const LazyInfoView = lazy(() => import("../info-view"))
+const LazyCommandPalette = lazy(() => import("../command-palette"))
+const LazyBackgroundProcessOutputDialog = lazy(() =>
+  import("../background-process-output-dialog").then((module) => ({ default: module.BackgroundProcessOutputDialog })),
+)
+const LazyPermissionApprovalModal = lazy(() => import("../permission-approval-modal"))
+
 interface InstanceShellProps {
   instance: Instance
   // Provided by App-level instance tabs; lets us pause heavy rendering
@@ -834,7 +839,9 @@ const InstanceShell2: Component<InstanceShellProps> = (props) => {
             }
           >
             <div class="info-view-pane flex flex-col flex-1 min-h-0 overflow-y-auto">
-              <InfoView instanceId={props.instance.id} />
+              <Suspense fallback={<div class="flex-1 min-h-0" />}>
+                <LazyInfoView instanceId={props.instance.id} />
+              </Suspense>
             </div>
           </Show>
         </Box>
@@ -850,30 +857,49 @@ const InstanceShell2: Component<InstanceShellProps> = (props) => {
         class="instance-shell2 flex flex-col flex-1 min-h-0"
         data-instance-id={props.instance.id}
       >
-        <Show when={hasSessions()} fallback={<InstanceWelcomeView instance={props.instance} />}>
+        <Show
+          when={hasSessions()}
+          fallback={
+            <Suspense fallback={<div class="flex-1 min-h-0" />}>
+              <LazyInstanceWelcomeView instance={props.instance} />
+            </Suspense>
+          }
+        >
           {sessionLayout}
         </Show>
       </div>
 
-      <CommandPalette
-        open={paletteOpen()}
-        onClose={() => hideCommandPalette(props.instance.id)}
-        commands={instancePaletteCommands()}
-        onExecute={props.onExecuteCommand}
-      />
+      <Show when={paletteOpen()}>
+        <Suspense fallback={null}>
+          <LazyCommandPalette
+            open={paletteOpen()}
+            onClose={() => hideCommandPalette(props.instance.id)}
+            commands={instancePaletteCommands()}
+            onExecute={props.onExecuteCommand}
+          />
+        </Suspense>
+      </Show>
 
-      <BackgroundProcessOutputDialog
-        open={showBackgroundOutput()}
-        instanceId={props.instance.id}
-        process={selectedBackgroundProcess()}
-        onClose={closeBackgroundOutput}
-      />
+      <Show when={showBackgroundOutput()}>
+        <Suspense fallback={null}>
+          <LazyBackgroundProcessOutputDialog
+            open={showBackgroundOutput()}
+            instanceId={props.instance.id}
+            process={selectedBackgroundProcess()}
+            onClose={closeBackgroundOutput}
+          />
+        </Suspense>
+      </Show>
 
-      <PermissionApprovalModal
-        instanceId={props.instance.id}
-        isOpen={permissionModalOpen()}
-        onClose={() => setPermissionModalOpen(false)}
-      />
+      <Show when={permissionModalOpen()}>
+        <Suspense fallback={null}>
+          <LazyPermissionApprovalModal
+            instanceId={props.instance.id}
+            isOpen={permissionModalOpen()}
+            onClose={() => setPermissionModalOpen(false)}
+          />
+        </Suspense>
+      </Show>
     </>
   )
 }
diff --git a/packages/ui/src/lib/i18n/index.tsx b/packages/ui/src/lib/i18n/index.tsx
index a63e53f1..f9949de2 100644
--- a/packages/ui/src/lib/i18n/index.tsx
+++ b/packages/ui/src/lib/i18n/index.tsx
@@ -2,11 +2,6 @@ import { createContext, createEffect, createMemo, createSignal, onCleanup, onMou
 import type { ParentComponent } from "solid-js"
 import { useConfig } from "../../stores/preferences"
 import { enMessages } from "./messages/en"
-import { esMessages } from "./messages/es"
-import { frMessages } from "./messages/fr"
-import { ruMessages } from "./messages/ru"
-import { jaMessages } from "./messages/ja"
-import { zhHansMessages } from "./messages/zh-Hans"
 
 type Messages = Record<string, string>
 
@@ -16,13 +11,16 @@ export type Locale = "en" | "es" | "fr" | "ru" | "ja" | "zh-Hans"
 
 const SUPPORTED_LOCALES: readonly Locale[] = ["en", "es", "fr", "ru", "ja", "zh-Hans"] as const
 
-const messagesByLocale: Record<Locale, Messages> = {
-  en: enMessages,
-  es: esMessages,
-  fr: frMessages,
-  ru: ruMessages,
-  ja: jaMessages,
-  "zh-Hans": zhHansMessages,
+const localeMessagesCache = new Map<Locale, Messages>([["en", enMessages]])
+const localeMessagesPromises = new Map<Locale, Promise<Messages>>()
+
+const localeLoaders: Record<Locale, () => Promise<Messages>> = {
+  en: async () => enMessages,
+  es: async () => (await import("./messages/es")).esMessages,
+  fr: async () => (await import("./messages/fr")).frMessages,
+  ru: async () => (await import("./messages/ru")).ruMessages,
+  ja: async () => (await import("./messages/ja")).jaMessages,
+  "zh-Hans": async () => (await import("./messages/zh-Hans")).zhHansMessages,
 }
 
 function normalizeLocaleTag(value: string): string {
@@ -84,8 +82,45 @@ function translateFrom(messages: Messages, key: string, params?: TranslateParams
 }
 
 const [globalRevision, setGlobalRevision] = createSignal(0)
-const initialGlobalLocale: Locale = detectNavigatorLocale() ?? "en"
-let globalMessages: Messages = messagesByLocale[initialGlobalLocale]
+let globalMessages: Messages = enMessages
+
+function getMessagesForLocale(locale: Locale): Messages {
+  return localeMessagesCache.get(locale) ?? enMessages
+}
+
+async function loadLocaleMessages(locale: Locale): Promise<Messages> {
+  const cached = localeMessagesCache.get(locale)
+  if (cached) {
+    return cached
+  }
+
+  const pending = localeMessagesPromises.get(locale)
+  if (pending) {
+    return pending
+  }
+
+  const loader = localeLoaders[locale]
+  const promise = loader()
+    .then((messages) => {
+      localeMessagesCache.set(locale, messages)
+      localeMessagesPromises.delete(locale)
+      return messages
+    })
+    .catch((error) => {
+      localeMessagesPromises.delete(locale)
+      throw error
+    })
+
+  localeMessagesPromises.set(locale, promise)
+  return promise
+}
+
+export async function preloadLocaleMessages(preferredLocale?: string | null): Promise<Locale> {
+  const resolvedLocale = matchSupportedLocale(preferredLocale ?? undefined) ?? detectNavigatorLocale() ?? "en"
+  globalMessages = await loadLocaleMessages(resolvedLocale)
+  setGlobalRevision((value) => value + 1)
+  return resolvedLocale
+}
 
 export function tGlobal(key: string, params?: TranslateParams): string {
   globalRevision()
@@ -102,8 +137,7 @@ const I18nContext = createContext<I18nContextValue>()
 export const I18nProvider: ParentComponent = (props) => {
   const { preferences } = useConfig()
   const [detectedLocale, setDetectedLocale] = createSignal<Locale>("en")
-
-  const previousMessages = globalMessages
+  const [resolvedLocale, setResolvedLocale] = createSignal<Locale>("en")
 
   onMount(() => {
     const detected = detectNavigatorLocale()
@@ -115,19 +149,42 @@ export const I18nProvider: ParentComponent = (props) => {
     return configured ?? detectedLocale() ?? "en"
   })
 
-  const messages = createMemo<Messages>(() => messagesByLocale[locale()])
+  const messages = createMemo<Messages>(() => getMessagesForLocale(resolvedLocale()))
 
   function t(key: string, params?: TranslateParams): string {
     return translateFrom(messages(), key, params)
   }
 
   createEffect(() => {
-    globalMessages = messages()
-    setGlobalRevision((value) => value + 1)
+    const nextLocale = locale()
+    let cancelled = false
+
+    void loadLocaleMessages(nextLocale)
+      .then((loadedMessages) => {
+        if (cancelled) {
+          return
+        }
+        localeMessagesCache.set(nextLocale, loadedMessages)
+        setResolvedLocale(nextLocale)
+        globalMessages = loadedMessages
+        setGlobalRevision((value) => value + 1)
+      })
+      .catch(() => {
+        if (cancelled) {
+          return
+        }
+        setResolvedLocale("en")
+        globalMessages = enMessages
+        setGlobalRevision((value) => value + 1)
+      })
+
+    onCleanup(() => {
+      cancelled = true
+    })
   })
 
   onCleanup(() => {
-    globalMessages = previousMessages
+    globalMessages = enMessages
     setGlobalRevision((value) => value + 1)
   })
 
diff --git a/packages/ui/src/main.tsx b/packages/ui/src/main.tsx
index c0a1b4ff..cc6c6f1e 100644
--- a/packages/ui/src/main.tsx
+++ b/packages/ui/src/main.tsx
@@ -4,7 +4,7 @@ import { ThemeProvider } from "./lib/theme"
 import { ConfigProvider } from "./stores/preferences"
 import { InstanceConfigProvider } from "./stores/instance-config"
 import { runtimeEnv } from "./lib/runtime-env"
-import { I18nProvider } from "./lib/i18n"
+import { I18nProvider, preloadLocaleMessages } from "./lib/i18n"
 import { storage } from "./lib/storage"
 import "./index.css"
 import "@git-diff-view/solid/styles/diff-view-pure.css"
@@ -32,14 +32,18 @@ async function bootstrap() {
     try {
       const uiConfig = await storage.loadConfigOwner("ui")
       const theme = (uiConfig as any)?.theme ?? "system"
+      const locale = (uiConfig as any)?.settings?.locale
 
       if (theme === "system") {
         document.documentElement.removeAttribute("data-theme")
       } else {
         document.documentElement.setAttribute("data-theme", theme)
       }
+
+      await preloadLocaleMessages(typeof locale === "string" ? locale : undefined)
     } catch {
       // If config fails to load, fall back to CSS defaults.
+      await preloadLocaleMessages(undefined)
     }
   }