diff --git a/frontend/nginx.conf b/frontend/nginx.conf
index ba4d9aa..a8a42be 100644
--- a/frontend/nginx.conf
+++ b/frontend/nginx.conf
@@ -1,11 +1,42 @@
 server {
   listen 80;
 
+  # The bundle is ~770 kB of JavaScript and ~85 kB of CSS, and nginx's base
+  # image ships gzip commented out — so every first load shipped all of it
+  # uncompressed. Roughly a third of the bytes with this on.
+  gzip on;
+  gzip_vary on;
+  gzip_min_length 1024;
+  gzip_proxied any;
+  gzip_types
+    application/javascript
+    application/json
+    application/manifest+json
+    application/wasm
+    image/svg+xml
+    text/css
+    text/plain;
+
   location / {
     root /usr/share/nginx/html;
     index index.html index.htm;
     try_files $uri /index.html =404;
   }
 
+  # Vite puts a content hash in every asset's name, so one can never change
+  # under its URL. Without this each of the ~50 of them cost a 304 round trip
+  # on every reload.
+  location /assets/ {
+    root /usr/share/nginx/html;
+    add_header Cache-Control "public, max-age=31536000, immutable";
+  }
+
+  # The one file that must not be cached: it is what names the current
+  # assets, so a stale copy pins the browser to the previous build.
+  location = /index.html {
+    root /usr/share/nginx/html;
+    add_header Cache-Control "no-cache";
+  }
+
   include /etc/nginx/extra-conf.d/*.conf;
 }
diff --git a/frontend/src/components/Common/GlobalSearch.tsx b/frontend/src/components/Common/GlobalSearch.tsx
index 4dbdba1..efc524e 100644
--- a/frontend/src/components/Common/GlobalSearch.tsx
+++ b/frontend/src/components/Common/GlobalSearch.tsx
@@ -31,6 +31,11 @@ export const searchQueryOptions = () => ({
 })
 
 /** The categories, in the order they are offered, with what to draw each as. */
+//: The most entries one group shows. cmdk scores what is mounted, so this is
+//: a cap on what is offered rather than on what is searched — and twenty of a
+//: kind is already more than anybody reads before typing another letter.
+const GROUP_CAP = 20
+
 const GROUPS: {
   category: SearchEntry["category"]
   label: string
@@ -58,8 +63,10 @@ function hint(entry: SearchEntry): string {
  * The whole index arrives in one fetch and `cmdk` does the matching, so results
  * narrow as they are typed without a round trip per keystroke.
  *
- * ponytail: every entry is rendered and cmdk hides the ones that do not match.
- * Cap the groups if an installation ever grows big enough to feel it.
+ * cmdk does the matching over what is mounted, so the entries are bucketed by
+ * category once per fetch rather than filtered nine times per keystroke, and
+ * each group is capped — a list nobody can scroll to the end of is not a
+ * better answer than its first twenty.
  */
 export function GlobalSearch({
   open,
@@ -79,6 +86,15 @@ export function GlobalSearch({
 
   const entries = data ?? []
   const typing = query.trim().length > 0
+  // One pass over the index rather than one per group — nine passes over
+  // every entry on each keystroke. Not memoised: the component returns early
+  // while closed, so a hook cannot go here, and one pass is already the win.
+  const byCategory = new Map<string, SearchEntry[]>()
+  for (const entry of entries) {
+    const bucket = byCategory.get(entry.category)
+    if (bucket) bucket.push(entry)
+    else byCategory.set(entry.category, [entry])
+  }
 
   const go = (entry: SearchEntry) => {
     onOpenChange(false)
@@ -144,9 +160,7 @@ export function GlobalSearch({
           <>
             <CommandEmpty>Nothing matches that.</CommandEmpty>
             {GROUPS.map(({ category, label, icon: Icon }) => {
-              const found = entries.filter(
-                (entry) => entry.category === category,
-              )
+              const found = (byCategory.get(category) ?? []).slice(0, GROUP_CAP)
               if (found.length === 0) return null
               return (
                 <CommandGroup key={category} heading={label}>
diff --git a/frontend/src/components/Dashboard/widgets.tsx b/frontend/src/components/Dashboard/widgets.tsx
index 63e2c36..a6fa019 100644
--- a/frontend/src/components/Dashboard/widgets.tsx
+++ b/frontend/src/components/Dashboard/widgets.tsx
@@ -1,4 +1,6 @@
+import { TriangleAlert } from "lucide-react"
 import { useState } from "react"
+import { ErrorBoundary } from "react-error-boundary"
 
 import type { WidgetDef } from "@/client"
 import { cn } from "@/lib/utils"
@@ -637,5 +639,22 @@ export function WidgetBody({ widget, dashboard }: WidgetProps) {
       </p>
     )
   }
-  return <Renderer widget={widget} dashboard={dashboard} />
+  return (
+    // Per tile, because a dashboard is often the only thing on a screen
+    // nobody is standing at: one widget whose config the renderer cannot make
+    // sense of used to throw past every ancestor and leave a wall panel
+    // blank, with no navigation to recover from.
+    <ErrorBoundary fallback={<WidgetFailed />} resetKeys={[widget.id]}>
+      <Renderer widget={widget} dashboard={dashboard} />
+    </ErrorBoundary>
+  )
+}
+
+function WidgetFailed() {
+  return (
+    <p className="flex h-full items-center justify-center gap-2 text-muted-foreground text-sm">
+      <TriangleAlert className="size-4 shrink-0" aria-hidden />
+      This tile could not be drawn.
+    </p>
+  )
 }
diff --git a/frontend/src/components/Flow/FlowEditor.tsx b/frontend/src/components/Flow/FlowEditor.tsx
index 69e0d76..3f2da2b 100644
--- a/frontend/src/components/Flow/FlowEditor.tsx
+++ b/frontend/src/components/Flow/FlowEditor.tsx
@@ -45,6 +45,8 @@ import {
 import useCustomToast from "@/hooks/useCustomToast"
 import { useIsMobile } from "@/hooks/useMobile"
 import { scaleIn } from "@/lib/motion"
+import { notify } from "@/lib/notificationStore"
+import { safeStorage } from "@/lib/safeStorage"
 import { inCodeEditor, useShortcuts } from "@/lib/shortcuts"
 import { cn } from "@/lib/utils"
 import { CanvasTitle } from "./CanvasTitle"
@@ -999,10 +1001,16 @@ function FlowEditorInner({
         }),
     ).catch(() => undefined)
 
-    localStorage.setItem(
+    // A multi-node copy carries whole Python sources, which can genuinely
+    // reach the origin's quota — and a throw from a key handler would take
+    // the app down rather than the copy.
+    const stored = safeStorage.set(
       CLIPBOARD_KEY,
       JSON.stringify({ nodes: picked, sources } satisfies NodeClipboard),
     )
+    if (!stored) {
+      notify("That is too much to copy — the browser store is full.", "error")
+    }
   }, [canvasNodes, definitions, flowName, selectedId, sourceTypes])
 
   /**
@@ -1011,7 +1019,7 @@ function FlowEditorInner({
    * the definition is on its way.
    */
   const pasteNodes = useCallback(() => {
-    const stored = localStorage.getItem(CLIPBOARD_KEY)
+    const stored = safeStorage.get(CLIPBOARD_KEY)
     if (!stored) return
     let clipboard: NodeClipboard
     try {
diff --git a/frontend/src/components/Flow/LogsPanel.tsx b/frontend/src/components/Flow/LogsPanel.tsx
index 849e80d..2348782 100644
--- a/frontend/src/components/Flow/LogsPanel.tsx
+++ b/frontend/src/components/Flow/LogsPanel.tsx
@@ -82,7 +82,16 @@ export function LogsTrigger({
  * Opening it is not only the dock's to do: a failing node points straight at
  * its own traceback, which is why the open state lives in the editor.
  */
-export function LogsPanel({
+export function LogsPanel(props: { flow: string } & LogsFilter) {
+  // The dock renders this unconditionally and the `AnimatePresence` inside
+  // decides whether to draw — so with the panel shut it still subscribed to
+  // the log store and re-filtered five hundred lines on every line a flow
+  // published. Nothing below runs until it is open.
+  if (!props.open) return null
+  return <OpenLogsPanel {...props} />
+}
+
+function OpenLogsPanel({
   flow,
   open,
   node,
diff --git a/frontend/src/components/Flow/liveStore.ts b/frontend/src/components/Flow/liveStore.ts
index ce72b10..e18be4c 100644
--- a/frontend/src/components/Flow/liveStore.ts
+++ b/frontend/src/components/Flow/liveStore.ts
@@ -297,6 +297,25 @@ export function useEngineEvents(): EngineEvent[] {
   )
 }
 
+/**
+ * The minute the newest engine event landed in, or 0 for none yet.
+ *
+ * A scalar, so a subscriber that only wants "has something gone wrong
+ * lately" re-renders when the answer changes rather than on every event.
+ * `recordEngineEvent` allocates a new array each time, so subscribing to the
+ * array itself means a flapping node re-renders whatever is watching — which
+ * on Home is two uPlot charts that rebuild their series from scratch.
+ */
+export function useEngineEventMinute(): number {
+  return useSyncExternalStore(
+    (listener) => subscribeKey("engine", listener),
+    () =>
+      engineEvents.length
+        ? Math.floor(engineEvents[engineEvents.length - 1].ts / 60)
+        : 0,
+  )
+}
+
 /** Increments each time the node publishes something. */
 export function useNodeEmits(nodeId: string): number {
   return useSyncExternalStore(
diff --git a/frontend/src/components/Health/HealthActivity.tsx b/frontend/src/components/Health/HealthActivity.tsx
index 4e4dbfd..f3bfca4 100644
--- a/frontend/src/components/Health/HealthActivity.tsx
+++ b/frontend/src/components/Health/HealthActivity.tsx
@@ -5,7 +5,7 @@ import { useEffect, useState } from "react"
 import type { EventRow, HistoryPoint } from "@/client"
 import type { Range } from "@/components/Common/RangePicker"
 import { UplotChart } from "@/components/Common/UplotChart"
-import { useEngineEvents } from "@/components/Flow/liveStore"
+import { useEngineEventMinute } from "@/components/Flow/liveStore"
 import { PANEL_SECTION } from "@/components/Flow/SidePanel"
 import { Button } from "@/components/ui/button"
 import { cn, dur, si } from "@/lib/utils"
@@ -218,7 +218,7 @@ function Failure({ event }: { event: EventRow }) {
  * the charts are drawn from rather than however far their newest rows reach.
  */
 export function HealthActivity({ range }: { range: Range }) {
-  const live = useEngineEvents()
+  const seen = useEngineEventMinute()
   const queryClient = useQueryClient()
   const runsAt = useMoment()
   const failuresAt = useMoment()
@@ -241,8 +241,9 @@ export function HealthActivity({ range }: { range: Range }) {
   //
   // The newest event's minute, not the count: the count stops changing once the
   // ring is full, and a per-event key would let a flapping node restart the
-  // timer forever without it ever firing.
-  const seen = live.length ? Math.floor(live[live.length - 1].ts / 60) : 0
+  // timer forever without it ever firing. Subscribed to as that scalar rather
+  // than as the events array, so an event inside a minute already seen does
+  // not re-render the two charts below.
   useEffect(() => {
     if (!seen) return
     const timer = setTimeout(() => {
diff --git a/frontend/src/components/theme-provider.tsx b/frontend/src/components/theme-provider.tsx
index 9d9d9d4..2d91fb4 100644
--- a/frontend/src/components/theme-provider.tsx
+++ b/frontend/src/components/theme-provider.tsx
@@ -6,6 +6,8 @@ import {
   useState,
 } from "react"
 
+import { safeStorage } from "@/lib/safeStorage"
+
 export type Theme = "dark" | "light" | "system"
 
 type ThemeProviderProps = {
@@ -37,7 +39,7 @@ export function ThemeProvider({
   const [theme, setTheme] = useState<Theme>(
     () =>
       (typeof localStorage !== "undefined"
-        ? (localStorage.getItem(storageKey) as Theme)
+        ? (safeStorage.get(storageKey) as Theme)
         : null) || defaultTheme,
   )
 
@@ -99,7 +101,7 @@ export function ThemeProvider({
     theme,
     resolvedTheme,
     setTheme: (theme: Theme) => {
-      localStorage.setItem(storageKey, theme)
+      safeStorage.set(storageKey, theme)
       setTheme(theme)
     },
   }
diff --git a/frontend/src/hooks/useAuth.ts b/frontend/src/hooks/useAuth.ts
index 67ba127..6828fa6 100644
--- a/frontend/src/hooks/useAuth.ts
+++ b/frontend/src/hooks/useAuth.ts
@@ -10,6 +10,7 @@ import {
 } from "@/client"
 import { liveStore } from "@/components/Flow/liveStore"
 import { isPortal } from "@/lib/portal"
+import { safeStorage } from "@/lib/safeStorage"
 import { handleError } from "@/utils"
 import useCustomToast from "./useCustomToast"
 
@@ -17,7 +18,7 @@ const isLoggedIn = () => {
   // Under a portal the credential comes with the page rather than from
   // storage, and the sign-in already happened there.
   if (isPortal()) return true
-  return localStorage.getItem("access_token") !== null
+  return safeStorage.get("access_token") !== null
 }
 
 /**
@@ -58,7 +59,7 @@ const useAuth = () => {
     const response = await LoginService.loginAccessToken({
       formData: data,
     })
-    localStorage.setItem("access_token", response.access_token)
+    safeStorage.set("access_token", response.access_token)
   }
 
   const loginMutation = useMutation({
@@ -72,7 +73,7 @@ const useAuth = () => {
   })
 
   const logout = () => {
-    localStorage.removeItem("access_token")
+    safeStorage.remove("access_token")
     // Live values belong to the session that was watching them.
     liveStore.reset()
     navigate({ to: "/login" })
diff --git a/frontend/src/lib/safeStorage.ts b/frontend/src/lib/safeStorage.ts
new file mode 100644
index 0000000..961be95
--- /dev/null
+++ b/frontend/src/lib/safeStorage.ts
@@ -0,0 +1,40 @@
+/**
+ * `localStorage` that cannot throw.
+ *
+ * Reaching `window.localStorage` at all raises `SecurityError` where the
+ * browser is set to block site data, and `setItem` raises `QuotaExceededError`
+ * once the origin's five megabytes are full — which the flow editor's node
+ * clipboard, carrying whole Python sources, can genuinely reach. Either one
+ * thrown from an event handler escapes to `window.onerror`, and with a single
+ * error boundary at the root that blanks the app.
+ *
+ * The pre-paint theme script in `index.html` already guards its own read this
+ * way; this is the same thing for everything that runs after it.
+ */
+export const safeStorage = {
+  get(key: string): string | null {
+    try {
+      return localStorage.getItem(key)
+    } catch {
+      return null
+    }
+  },
+
+  /** Whether it was actually stored, for the rare caller that wants to know. */
+  set(key: string, value: string): boolean {
+    try {
+      localStorage.setItem(key, value)
+      return true
+    } catch {
+      return false
+    }
+  },
+
+  remove(key: string): void {
+    try {
+      localStorage.removeItem(key)
+    } catch {
+      // Nothing to clean up if it was never reachable.
+    }
+  },
+}
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index b3a52a1..2ccb887 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -16,6 +16,7 @@ import "./index.css"
 import { connectionStore, offlineDetail } from "./lib/connectionStore"
 import { notify } from "./lib/notificationStore"
 import { apiToken, appPath, appRoute, portalConfig } from "./lib/portal"
+import { safeStorage } from "./lib/safeStorage"
 import { routeTree } from "./routeTree.gen"
 
 const portal = portalConfig()
@@ -58,7 +59,7 @@ const handleApiError = (error: Error) => {
     // A paired wall panel has no login screen to go back to — it asks for a
     // new code instead.
     if (appRoute().startsWith("/panel")) {
-      localStorage.removeItem("access_token")
+      safeStorage.remove("access_token")
       window.location.href = appPath("/panel")
       return
     }
@@ -68,7 +69,7 @@ const handleApiError = (error: Error) => {
       window.location.href = `${portal.portalUrl}?reauth=${portal.installationId}`
       return
     }
-    localStorage.removeItem("access_token")
+    safeStorage.remove("access_token")
     window.location.href = appPath("/login")
     return
   }
@@ -94,6 +95,14 @@ const queryClient = new QueryClient({
     queries: {
       // Retrying an expired session only delays the trip to the login screen.
       retry: (count, error) => !isPointlessToRetry(error) && count < 3,
+      // Below every poll interval on any screen, so nothing polls less often
+      // than it did — but a route that mounts twice in a few seconds, or a
+      // tab coming back to the foreground, stops refetching everything it
+      // touches. Home alone reads about ten queries.
+      staleTime: 5_000,
+      // The socket pushes what changes, and a reconnect invalidates what it
+      // feeds, so a focus event has nothing of its own to tell us.
+      refetchOnWindowFocus: false,
     },
     mutations: {
       retry: false,
diff --git a/frontend/src/routes/_layout.tsx b/frontend/src/routes/_layout.tsx
index 63bd00f..771dfd7 100644
--- a/frontend/src/routes/_layout.tsx
+++ b/frontend/src/routes/_layout.tsx
@@ -1,6 +1,7 @@
 import { createFileRoute, Outlet, redirect } from "@tanstack/react-router"
 
 import { ConnectionNotice } from "@/components/Common/ConnectionNotice"
+import ErrorComponent from "@/components/Common/ErrorComponent"
 import { Footer } from "@/components/Common/Footer"
 import { useFlowSocket } from "@/components/Flow/useFlowSocket"
 import AppSidebar from "@/components/Sidebar/AppSidebar"
@@ -13,6 +14,10 @@ import { isLoggedIn } from "@/hooks/useAuth"
 
 export const Route = createFileRoute("/_layout")({
   component: Layout,
+  // Inside the shell rather than at the root, so a screen that throws leaves
+  // the sidebar standing and somebody can navigate away from it. The root's
+  // own boundary replaces the whole app, navigation included.
+  errorComponent: () => <ErrorComponent />,
   beforeLoad: async () => {
     if (!isLoggedIn()) {
       throw redirect({