diff --git a/package-lock.json b/package-lock.json
index 74e165a..5249800 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,6 +16,7 @@
         "@tailwindcss/postcss": "^4.2.1",
         "@tanstack/react-query": "^5.90.21",
         "@tanstack/react-table": "^8.21.3",
+        "@tanstack/react-virtual": "^3.13.19",
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "cmdk": "^1.1.1",
@@ -4915,6 +4916,23 @@
         "react-dom": ">=16.8"
       }
     },
+    "node_modules/@tanstack/react-virtual": {
+      "version": "3.13.19",
+      "resolved": "https://registry.npmjs.org/@tanstack/react-virtual/-/react-virtual-3.13.19.tgz",
+      "integrity": "sha512-KzwmU1IbE0IvCZSm6OXkS+kRdrgW2c2P3Ho3NC+zZXWK6oObv/L+lcV/2VuJ+snVESRlMJ+w/fg4WXI/JzoNGQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@tanstack/virtual-core": "3.13.19"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      },
+      "peerDependencies": {
+        "react": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0",
+        "react-dom": "^16.8.0 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/@tanstack/table-core": {
       "version": "8.21.3",
       "resolved": "https://registry.npmjs.org/@tanstack/table-core/-/table-core-8.21.3.tgz",
@@ -4928,6 +4946,16 @@
         "url": "https://github.com/sponsors/tannerlinsley"
       }
     },
+    "node_modules/@tanstack/virtual-core": {
+      "version": "3.13.19",
+      "resolved": "https://registry.npmjs.org/@tanstack/virtual-core/-/virtual-core-3.13.19.tgz",
+      "integrity": "sha512-/BMP7kNhzKOd7wnDeB8NrIRNLwkf5AhCYCvtfZV2GXWbBieFm/el0n6LOAXlTi6ZwHICSNnQcIxRCWHrLzDY+g==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      }
+    },
     "node_modules/@tybys/wasm-util": {
       "version": "0.10.1",
       "resolved": "https://registry.npmjs.org/@tybys/wasm-util/-/wasm-util-0.10.1.tgz",
diff --git a/package.json b/package.json
index 0ae8245..b59b581 100644
--- a/package.json
+++ b/package.json
@@ -24,6 +24,7 @@
     "@tailwindcss/postcss": "^4.2.1",
     "@tanstack/react-query": "^5.90.21",
     "@tanstack/react-table": "^8.21.3",
+    "@tanstack/react-virtual": "^3.13.19",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
diff --git a/src/app/(app)/layout.tsx b/src/app/(app)/layout.tsx
index bf4dd68..7bb7c6a 100644
--- a/src/app/(app)/layout.tsx
+++ b/src/app/(app)/layout.tsx
@@ -2,7 +2,7 @@ import { Suspense } from "react";
 import { Sidebar, MobileSidebar } from "@/components/layout/sidebar";
 import { Topbar } from "@/components/layout/topbar";
 import { QueryProvider } from "@/components/query-provider";
-import { CommandPalette } from "@/components/command-palette";
+import { LazyCommandPalette } from "@/components/lazy-command-palette";
 
 export default function AppLayout({ children }: { children: React.ReactNode }) {
   return (
@@ -11,13 +11,13 @@ export default function AppLayout({ children }: { children: React.ReactNode }) {
         <Sidebar />
         <div className="flex flex-1 flex-col overflow-hidden">
           <Topbar />
-          <main className="flex-1 overflow-auto p-4 md:p-6">
+          <main id="main-content" className="flex-1 overflow-auto p-4 md:p-6">
             <Suspense>{children}</Suspense>
           </main>
         </div>
       </div>
       <MobileSidebar />
-      <CommandPalette />
+      <LazyCommandPalette />
     </QueryProvider>
   );
 }
diff --git a/src/app/(app)/projects/[projectId]/board/page.tsx b/src/app/(app)/projects/[projectId]/board/page.tsx
index f1916ab..9ff91ce 100644
--- a/src/app/(app)/projects/[projectId]/board/page.tsx
+++ b/src/app/(app)/projects/[projectId]/board/page.tsx
@@ -1,10 +1,15 @@
 "use client";
 
+import dynamic from "next/dynamic";
 import { useParams } from "next/navigation";
 import { useDeliverables, useUpdateStageStatus } from "@/hooks/use-deliverables";
-import { KanbanBoard } from "@/components/views/kanban-board";
 import { Skeleton } from "@/components/ui/skeleton";
 
+const KanbanBoard = dynamic(
+  () => import("@/components/views/kanban-board").then((m) => m.KanbanBoard),
+  { ssr: false }
+);
+
 export default function BoardViewPage() {
   const { projectId } = useParams<{ projectId: string }>();
   const { data: deliverables, isLoading } = useDeliverables(projectId);
diff --git a/src/app/(app)/projects/[projectId]/timeline/page.tsx b/src/app/(app)/projects/[projectId]/timeline/page.tsx
index f2ea743..0a2abf2 100644
--- a/src/app/(app)/projects/[projectId]/timeline/page.tsx
+++ b/src/app/(app)/projects/[projectId]/timeline/page.tsx
@@ -1,10 +1,15 @@
 "use client";
 
+import dynamic from "next/dynamic";
 import { useParams } from "next/navigation";
 import { useDeliverables } from "@/hooks/use-deliverables";
-import { GanttTimeline } from "@/components/views/gantt-timeline";
 import { Skeleton } from "@/components/ui/skeleton";
 
+const GanttTimeline = dynamic(
+  () => import("@/components/views/gantt-timeline").then((m) => m.GanttTimeline),
+  { ssr: false }
+);
+
 export default function TimelineViewPage() {
   const { projectId } = useParams<{ projectId: string }>();
   const { data: deliverables, isLoading } = useDeliverables(projectId);
diff --git a/src/app/error.tsx b/src/app/error.tsx
index fb247a6..a33800f 100644
--- a/src/app/error.tsx
+++ b/src/app/error.tsx
@@ -16,9 +16,9 @@ export default function GlobalError({
   }, [error]);
 
   return (
-    <div className="flex min-h-screen items-center justify-center p-6">
+    <div className="flex min-h-screen items-center justify-center p-6" role="alert">
       <div className="max-w-md text-center">
-        <AlertTriangle className="mx-auto mb-4 h-12 w-12 text-[var(--accent)]" />
+        <AlertTriangle className="mx-auto mb-4 h-12 w-12 text-[var(--accent)]" aria-hidden="true" />
         <h1 className="font-heading text-2xl font-bold">
           Something went wrong
         </h1>
diff --git a/src/app/globals.css b/src/app/globals.css
index 0604426..8a1fed2 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -114,4 +114,27 @@
   h1, h2, h3, h4, h5, h6 {
     font-family: var(--font-heading);
   }
+
+  /* Focus-visible ring for keyboard navigation */
+  :focus-visible {
+    @apply outline-2 outline-offset-2 outline-[var(--ring)];
+  }
+
+  /* Remove default focus outlines for mouse users */
+  :focus:not(:focus-visible) {
+    outline: none;
+  }
+
+  /* Screen-reader only utility */
+  .sr-only {
+    position: absolute;
+    width: 1px;
+    height: 1px;
+    padding: 0;
+    margin: -1px;
+    overflow: hidden;
+    clip: rect(0, 0, 0, 0);
+    white-space: nowrap;
+    border-width: 0;
+  }
 }
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index 5269a33..0c89d17 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -41,6 +41,12 @@ export default function RootLayout({
       suppressHydrationWarning
     >
       <body>
+        <a
+          href="#main-content"
+          className="fixed left-2 top-2 z-[100] -translate-y-16 rounded-md bg-[var(--primary)] px-4 py-2 text-sm font-medium text-[var(--primary-foreground)] transition-transform focus:translate-y-0"
+        >
+          Skip to main content
+        </a>
         <ThemeProvider
           attribute="class"
           defaultTheme="system"
diff --git a/src/app/not-found.tsx b/src/app/not-found.tsx
index 9b33b05..1e0778e 100644
--- a/src/app/not-found.tsx
+++ b/src/app/not-found.tsx
@@ -6,7 +6,7 @@ export default function NotFound() {
   return (
     <div className="flex min-h-screen items-center justify-center p-6">
       <div className="max-w-md text-center">
-        <FileQuestion className="mx-auto mb-4 h-12 w-12 text-[var(--muted-foreground)]" />
+        <FileQuestion className="mx-auto mb-4 h-12 w-12 text-[var(--muted-foreground)]" aria-hidden="true" />
         <h1 className="font-heading text-4xl font-bold">404</h1>
         <p className="mt-2 text-sm text-[var(--muted-foreground)]">
           The page you're looking for doesn't exist.
diff --git a/src/components/deliverables/pipeline-progress.tsx b/src/components/deliverables/pipeline-progress.tsx
index 9d48be9..95f3373 100644
--- a/src/components/deliverables/pipeline-progress.tsx
+++ b/src/components/deliverables/pipeline-progress.tsx
@@ -26,7 +26,14 @@ export function PipelineProgress({ stages }: { stages: Stage[] }) {
   ).length;
 
   return (
-    <div className="space-y-1.5">
+    <div
+      className="space-y-1.5"
+      role="progressbar"
+      aria-valuenow={completed}
+      aria-valuemin={0}
+      aria-valuemax={sorted.length}
+      aria-label={`Pipeline progress: ${completed} of ${sorted.length} stages complete`}
+    >
       <div className="flex gap-0.5">
         {sorted.map((stage) => (
           <Tooltip key={stage.id} delayDuration={0}>
diff --git a/src/components/layout/breadcrumbs.tsx b/src/components/layout/breadcrumbs.tsx
index 7004c8b..05125e5 100644
--- a/src/components/layout/breadcrumbs.tsx
+++ b/src/components/layout/breadcrumbs.tsx
@@ -32,18 +32,19 @@ export function Breadcrumbs() {
   });
 
   return (
-    <nav className="flex items-center gap-1 text-sm">
+    <nav aria-label="Breadcrumb" className="flex items-center gap-1 text-sm">
       <Link
         href="/dashboard"
         className="text-[var(--muted-foreground)] transition-colors hover:text-[var(--foreground)]"
+        aria-label="Home"
       >
         <Home className="h-4 w-4" />
       </Link>
       {crumbs.map((crumb) => (
         <Fragment key={crumb.href}>
-          <ChevronRight className="h-3 w-3 text-[var(--muted-foreground)]" />
+          <ChevronRight className="h-3 w-3 text-[var(--muted-foreground)]" aria-hidden="true" />
           {crumb.isLast ? (
-            <span className="font-medium text-[var(--foreground)]">
+            <span className="font-medium text-[var(--foreground)]" aria-current="page">
               {crumb.label}
             </span>
           ) : (
diff --git a/src/components/layout/sidebar.tsx b/src/components/layout/sidebar.tsx
index f0dba28..e670edc 100644
--- a/src/components/layout/sidebar.tsx
+++ b/src/components/layout/sidebar.tsx
@@ -41,7 +41,7 @@ function NavLinks({
 
   return (
     <>
-      <nav className="flex-1 space-y-1 p-2">
+      <nav className="flex-1 space-y-1 p-2" aria-label="Main navigation">
         {navItems.map((item) => {
           const isActive =
             pathname === item.href || pathname.startsWith(item.href + "/");
@@ -79,7 +79,7 @@ function NavLinks({
 
       <Separator />
 
-      <nav className="space-y-1 p-2">
+      <nav className="space-y-1 p-2" aria-label="Settings">
         {bottomItems.map((item) => {
           const isActive = pathname === item.href;
           const Icon = item.icon;
@@ -127,6 +127,8 @@ export function Sidebar() {
         "hidden h-screen flex-col border-r bg-[var(--muted)] transition-all duration-200 md:flex",
         isCollapsed ? "w-16" : "w-64"
       )}
+      role="navigation"
+      aria-label="Sidebar"
     >
       {/* Logo / Title */}
       <div className="flex h-14 items-center gap-2 border-b px-4">
diff --git a/src/components/layout/topbar.tsx b/src/components/layout/topbar.tsx
index 969db2f..10a8363 100644
--- a/src/components/layout/topbar.tsx
+++ b/src/components/layout/topbar.tsx
@@ -52,7 +52,7 @@ export function Topbar() {
   const items = (notifications as any[]) ?? [];
 
   return (
-    <header className="flex h-14 items-center justify-between border-b bg-[var(--background)] px-4 md:px-6">
+    <header className="flex h-14 items-center justify-between border-b bg-[var(--background)] px-4 md:px-6" role="banner">
       <div className="flex items-center gap-2">
         <MobileMenuButton />
         <Breadcrumbs />
@@ -63,16 +63,29 @@ export function Topbar() {
 
         <Popover>
           <PopoverTrigger asChild>
-            <Button variant="ghost" size="icon" className="relative h-8 w-8">
+            <Button
+              variant="ghost"
+              size="icon"
+              className="relative h-8 w-8"
+              aria-label={
+                unreadCount > 0
+                  ? `Notifications, ${unreadCount} unread`
+                  : "Notifications"
+              }
+            >
               <Bell className="h-4 w-4" />
               {unreadCount > 0 && (
                 <Badge
                   variant="destructive"
                   className="absolute -right-1 -top-1 h-4 min-w-4 rounded-full p-0 text-[10px] leading-4"
+                  aria-hidden="true"
                 >
                   {unreadCount > 99 ? "99+" : unreadCount}
                 </Badge>
               )}
+              <span className="sr-only" aria-live="polite">
+                {unreadCount > 0 ? `${unreadCount} unread notifications` : ""}
+              </span>
             </Button>
           </PopoverTrigger>
           <PopoverContent align="end" className="w-80 p-0">
diff --git a/src/components/lazy-command-palette.tsx b/src/components/lazy-command-palette.tsx
new file mode 100644
index 0000000..3e003f7
--- /dev/null
+++ b/src/components/lazy-command-palette.tsx
@@ -0,0 +1,12 @@
+"use client";
+
+import dynamic from "next/dynamic";
+
+const CommandPalette = dynamic(
+  () => import("@/components/command-palette").then((m) => m.CommandPalette),
+  { ssr: false }
+);
+
+export function LazyCommandPalette() {
+  return <CommandPalette />;
+}
diff --git a/src/components/views/gantt-timeline.tsx b/src/components/views/gantt-timeline.tsx
index fc339c7..faad510 100644
--- a/src/components/views/gantt-timeline.tsx
+++ b/src/components/views/gantt-timeline.tsx
@@ -131,7 +131,11 @@ export function GanttTimeline({
   const chartWidth = totalDays * DAY_WIDTH;
 
   return (
-    <div className="overflow-auto rounded-md border">
+    <div
+      className="overflow-auto rounded-md border"
+      role="region"
+      aria-label="Gantt timeline chart"
+    >
       <div className="flex" style={{ minWidth: LABEL_WIDTH + chartWidth }}>
         {/* Labels column */}
         <div
diff --git a/src/components/views/kanban-board.tsx b/src/components/views/kanban-board.tsx
index 80ef10e..333f10e 100644
--- a/src/components/views/kanban-board.tsx
+++ b/src/components/views/kanban-board.tsx
@@ -105,7 +105,11 @@ export function KanbanBoard({
 
   return (
     <DragDropContext onDragEnd={onDragEnd}>
-      <div className="flex gap-4 overflow-x-auto pb-4">
+      <div
+        className="flex gap-4 overflow-x-auto pb-4"
+        role="region"
+        aria-label="Kanban board"
+      >
         {COLUMNS.map((column) => {
           const items = grouped.get(column.id) ?? [];
 
@@ -113,12 +117,15 @@ export function KanbanBoard({
             <div
               key={column.id}
               className="w-72 shrink-0 rounded-lg bg-[var(--muted)] p-3"
+              role="region"
+              aria-label={`${column.label} column, ${items.length} item${items.length !== 1 ? "s" : ""}`}
             >
               {/* Column header */}
               <div className="mb-3 flex items-center gap-2">
                 <div
                   className="h-2.5 w-2.5 rounded-full"
                   style={{ backgroundColor: column.color }}
+                  aria-hidden="true"
                 />
                 <span className="text-sm font-semibold">{column.label}</span>
                 <span className="ml-auto text-xs text-[var(--muted-foreground)]">