diff --git a/design/performance-note-list.pen b/design/performance-note-list.pen
new file mode 100644
index 00000000..afa6e41f
--- /dev/null
+++ b/design/performance-note-list.pen
@@ -0,0 +1,273 @@
+{
+  "version": "2.8",
+  "children": [
+    {
+      "type": "frame",
+      "id": "vl001",
+      "x": 0,
+      "y": 0,
+      "name": "Virtual List — Default State (9000+ notes)",
+      "theme": {"Mode": "Light"},
+      "clip": true,
+      "width": 300,
+      "height": 900,
+      "fill": "$--card",
+      "layout": "vertical",
+      "children": [
+        {
+          "type": "frame",
+          "id": "vl002",
+          "name": "Header",
+          "width": "fill_container",
+          "height": 45,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [0, 16],
+          "alignItems": "center",
+          "children": [
+            {"type": "text", "id": "vl003", "text": "Notes", "fontSize": 14, "fontWeight": 600, "fill": "$--foreground"},
+            {"type": "text", "id": "vl004", "text": "9,236 items", "fontSize": 11, "fill": "$--muted-foreground", "x": 200}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl005",
+          "name": "Virtualized Viewport",
+          "width": "fill_container",
+          "height": "fill_container",
+          "fill": "$--card",
+          "layout": "vertical",
+          "clip": true,
+          "children": [
+            {"type": "frame", "id": "vl006", "name": "NoteItem-visible-1", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl007", "text": "Build Laputa App", "fontSize": 13, "fontWeight": 600, "fill": "$--foreground"},
+              {"type": "text", "id": "vl008", "text": "This paragraph has bold text, italic text...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl009", "text": "2m ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl010", "name": "NoteItem-visible-2", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl011", "text": "Facebook Ads Strategy", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl012", "text": "Lookalike audiences convert 3x better...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl013", "text": "5h ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl014", "name": "NoteItem-visible-3", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl015", "text": "Quick Meeting 1", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl016", "text": "Key findings from the latest analysis...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl017", "text": "1d ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl018", "name": "NoteItem-visible-4", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl019", "text": "Advanced Strategy 2", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl020", "text": "Notes on process improvements...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl021", "text": "2d ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl022", "name": "NoteItem-visible-5-selected", "width": "fill_container", "height": 72, "fill": "#2383E210", "stroke": {"align": "inside", "thickness": {"left": 3, "bottom": 1}, "fill": "$--accent-blue"}, "padding": [14, 13], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl023", "text": "Daily Review 3", "fontSize": 13, "fontWeight": 600, "fill": "$--foreground"},
+              {"type": "text", "id": "vl024", "text": "Summary of decisions made during review...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl025", "text": "3d ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl026", "name": "NoteItem-visible-6", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl027", "text": "Weekly Plan 4", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl028", "text": "Action items and follow-ups...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl029", "text": "4d ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl030", "name": "scrollbar-indicator", "width": 6, "height": 40, "fill": "$--muted-foreground", "opacity": 0.3, "cornerRadius": 3, "x": 290, "y": 200}
+          ]
+        }
+      ]
+    },
+    {
+      "type": "frame",
+      "id": "vl100",
+      "x": 340,
+      "y": 0,
+      "name": "Virtual List — Scrolled Mid-list",
+      "theme": {"Mode": "Light"},
+      "clip": true,
+      "width": 300,
+      "height": 900,
+      "fill": "$--card",
+      "layout": "vertical",
+      "children": [
+        {
+          "type": "frame",
+          "id": "vl101",
+          "name": "Header",
+          "width": "fill_container",
+          "height": 45,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [0, 16],
+          "alignItems": "center",
+          "children": [
+            {"type": "text", "id": "vl102", "text": "Notes", "fontSize": 14, "fontWeight": 600, "fill": "$--foreground"}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl103",
+          "name": "Virtualized Viewport — items 4500-4512",
+          "width": "fill_container",
+          "height": "fill_container",
+          "fill": "$--card",
+          "layout": "vertical",
+          "clip": true,
+          "children": [
+            {"type": "frame", "id": "vl104", "name": "NoteItem-mid-1", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl105", "text": "Final Report 4501", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl106", "text": "Draft outline for upcoming deliverable.", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl107", "text": "Jan 15", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl108", "name": "NoteItem-mid-2", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl109", "text": "Revised Checklist 4502", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl110", "text": "Reference material for ongoing initiative.", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl111", "text": "Jan 14", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl112", "name": "NoteItem-mid-3", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl113", "text": "Archived Template 4503", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl114", "text": "Tracking progress on quarterly objectives.", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl115", "text": "Jan 13", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl116", "name": "NoteItem-mid-4", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl117", "text": "New Framework 4504", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl118", "text": "Comparison of different approaches.", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl119", "text": "Jan 12", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl120", "name": "scrollbar-indicator-mid", "width": 6, "height": 40, "fill": "$--muted-foreground", "opacity": 0.3, "cornerRadius": 3, "x": 290, "y": 440}
+          ]
+        }
+      ]
+    },
+    {
+      "type": "frame",
+      "id": "vl200",
+      "x": 680,
+      "y": 0,
+      "name": "Virtual List — Search Filtering",
+      "theme": {"Mode": "Light"},
+      "clip": true,
+      "width": 300,
+      "height": 900,
+      "fill": "$--card",
+      "layout": "vertical",
+      "children": [
+        {
+          "type": "frame",
+          "id": "vl201",
+          "name": "Header",
+          "width": "fill_container",
+          "height": 45,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [0, 16],
+          "alignItems": "center",
+          "children": [
+            {"type": "text", "id": "vl202", "text": "Notes", "fontSize": 14, "fontWeight": 600, "fill": "$--foreground"}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl203",
+          "name": "Search Bar",
+          "width": "fill_container",
+          "height": 40,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [8, 12],
+          "alignItems": "center",
+          "children": [
+            {"type": "frame", "id": "vl204", "name": "search-input", "width": "fill_container", "height": 32, "fill": "$--background", "cornerRadius": 6, "stroke": {"align": "inside", "thickness": 1, "fill": "$--border"}, "padding": [0, 8], "alignItems": "center", "children": [
+              {"type": "text", "id": "vl205", "text": "strategy", "fontSize": 13, "fill": "$--foreground"}
+            ]}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl206",
+          "name": "Filtered Results (23 matches)",
+          "width": "fill_container",
+          "height": "fill_container",
+          "fill": "$--card",
+          "layout": "vertical",
+          "clip": true,
+          "children": [
+            {"type": "frame", "id": "vl207", "name": "NoteItem-filtered-1", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl208", "text": "Facebook Ads Strategy", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl209", "text": "Lookalike audiences convert 3x better...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl210", "text": "5h ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl211", "name": "NoteItem-filtered-2", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl212", "text": "Advanced Strategy 2", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl213", "text": "Notes on process improvements...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl214", "text": "2d ago", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]},
+            {"type": "frame", "id": "vl215", "name": "NoteItem-filtered-3", "width": "fill_container", "height": 72, "fill": "$--card", "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"}, "padding": [14, 16], "layout": "vertical", "gap": 2, "children": [
+              {"type": "text", "id": "vl216", "text": "Quick Strategy 10", "fontSize": 13, "fontWeight": 500, "fill": "$--foreground"},
+              {"type": "text", "id": "vl217", "text": "Key findings from the latest analysis...", "fontSize": 12, "fill": "$--muted-foreground"},
+              {"type": "text", "id": "vl218", "text": "Jan 5", "fontSize": 10, "fill": "$--muted-foreground"}
+            ]}
+          ]
+        }
+      ]
+    },
+    {
+      "type": "frame",
+      "id": "vl300",
+      "x": 1020,
+      "y": 0,
+      "name": "Virtual List — Empty Search Result",
+      "theme": {"Mode": "Light"},
+      "clip": true,
+      "width": 300,
+      "height": 400,
+      "fill": "$--card",
+      "layout": "vertical",
+      "children": [
+        {
+          "type": "frame",
+          "id": "vl301",
+          "name": "Header",
+          "width": "fill_container",
+          "height": 45,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [0, 16],
+          "alignItems": "center",
+          "children": [
+            {"type": "text", "id": "vl302", "text": "Notes", "fontSize": 14, "fontWeight": 600, "fill": "$--foreground"}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl303",
+          "name": "Search Bar",
+          "width": "fill_container",
+          "height": 40,
+          "fill": "$--card",
+          "stroke": {"align": "inside", "thickness": {"bottom": 1}, "fill": "$--border"},
+          "padding": [8, 12],
+          "alignItems": "center",
+          "children": [
+            {"type": "frame", "id": "vl304", "name": "search-input", "width": "fill_container", "height": 32, "fill": "$--background", "cornerRadius": 6, "stroke": {"align": "inside", "thickness": 1, "fill": "$--border"}, "padding": [0, 8], "alignItems": "center", "children": [
+              {"type": "text", "id": "vl305", "text": "xyznonexistent", "fontSize": 13, "fill": "$--foreground"}
+            ]}
+          ]
+        },
+        {
+          "type": "frame",
+          "id": "vl306",
+          "name": "Empty State",
+          "width": "fill_container",
+          "height": "fill_container",
+          "fill": "$--card",
+          "layout": "vertical",
+          "justifyContent": "center",
+          "alignItems": "center",
+          "padding": [32, 16],
+          "children": [
+            {"type": "text", "id": "vl307", "text": "No matching notes", "fontSize": 13, "fill": "$--muted-foreground", "textAlign": "center"}
+          ]
+        }
+      ]
+    }
+  ],
+  "variables": {}
+}
\ No newline at end of file
diff --git a/src/components/NoteList.test.tsx b/src/components/NoteList.test.tsx
index 7b29ddda..8275d31f 100644
--- a/src/components/NoteList.test.tsx
+++ b/src/components/NoteList.test.tsx
@@ -748,3 +748,111 @@ describe('NoteList — trash view', () => {
     expect(screen.getByText('Trash is empty')).toBeInTheDocument()
   })
 })
+
+// --- Virtual list performance tests ---
+
+describe('NoteList — virtual list with large datasets', () => {
+  const makeEntry = (i: number, overrides?: Partial<VaultEntry>): VaultEntry => ({
+    path: `/vault/note/note-${i}.md`,
+    filename: `note-${i}.md`,
+    title: `Note ${i}`,
+    isA: 'Note',
+    aliases: [],
+    belongsTo: [],
+    relatedTo: [],
+    status: null,
+    owner: null,
+    cadence: null,
+    archived: false,
+    trashed: false,
+    trashedAt: null,
+    modifiedAt: 1700000000 - i * 60,
+    createdAt: null,
+    fileSize: 500,
+    snippet: `Content of note ${i}`,
+    relationships: {},
+    icon: null,
+    color: null,
+    order: null,
+    ...overrides,
+  })
+
+  it('renders 9000 entries without crashing', () => {
+    const largeDataset = Array.from({ length: 9000 }, (_, i) => makeEntry(i))
+    const { container } = render(
+      <NoteList entries={largeDataset} selection={allSelection} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    // Virtuoso mock renders all items; the real component only renders visible ones
+    expect(container.querySelector('[data-testid="virtuoso-mock"]')).toBeInTheDocument()
+  })
+
+  it('renders items from a large dataset via Virtuoso', () => {
+    const largeDataset = Array.from({ length: 500 }, (_, i) => makeEntry(i))
+    render(
+      <NoteList entries={largeDataset} selection={allSelection} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    expect(screen.getByText('Note 0')).toBeInTheDocument()
+    expect(screen.getByText('Note 499')).toBeInTheDocument()
+  })
+
+  it('search filters large dataset correctly', () => {
+    const entries = [
+      makeEntry(0, { title: 'Alpha Strategy' }),
+      ...Array.from({ length: 998 }, (_, i) => makeEntry(i + 1, { title: `Filler Note ${i + 1}` })),
+      makeEntry(999, { title: 'Beta Strategy' }),
+    ]
+    render(
+      <NoteList entries={entries} selection={allSelection} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    fireEvent.click(screen.getByTitle('Search notes'))
+    fireEvent.change(screen.getByPlaceholderText('Search notes...'), { target: { value: 'Strategy' } })
+    expect(screen.getByText('Alpha Strategy')).toBeInTheDocument()
+    expect(screen.getByText('Beta Strategy')).toBeInTheDocument()
+    expect(screen.queryByText('Filler Note 1')).not.toBeInTheDocument()
+  })
+
+  it('sorting works with large dataset', () => {
+    const entries = [
+      makeEntry(0, { title: 'Zebra', modifiedAt: 1000 }),
+      makeEntry(1, { title: 'Alpha', modifiedAt: 3000 }),
+      ...Array.from({ length: 100 }, (_, i) => makeEntry(i + 2, { title: `Mid ${i}`, modifiedAt: 2000 - i })),
+    ]
+    render(
+      <NoteList entries={entries} selection={allSelection} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    // Default sort is modified desc — Alpha (3000) should come first
+    const firstTitle = screen.getAllByText(/^Alpha$|^Zebra$/)[0]
+    expect(firstTitle.textContent).toBe('Alpha')
+  })
+
+  it('section group filter works with large mixed-type dataset', () => {
+    const entries = [
+      ...Array.from({ length: 100 }, (_, i) => makeEntry(i, { isA: 'Project', title: `Project ${i}` })),
+      ...Array.from({ length: 200 }, (_, i) => makeEntry(100 + i, { isA: 'Note', title: `Note ${i}` })),
+    ]
+    render(
+      <NoteList entries={entries} selection={{ kind: 'sectionGroup', type: 'Project' }} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    expect(screen.getByText('Project 0')).toBeInTheDocument()
+    expect(screen.queryByText('Note 0')).not.toBeInTheDocument()
+  })
+
+  it('selection highlighting works in virtualized list', () => {
+    const entries = Array.from({ length: 100 }, (_, i) => makeEntry(i))
+    const selected = entries[5]
+    render(
+      <NoteList entries={entries} selection={allSelection} selectedNote={selected} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    expect(screen.getByText('Note 5')).toBeInTheDocument()
+  })
+
+  it('click handler works on virtualized items', () => {
+    noopReplace.mockClear()
+    const entries = Array.from({ length: 100 }, (_, i) => makeEntry(i))
+    render(
+      <NoteList entries={entries} selection={allSelection} selectedNote={null} onSelectNote={noopSelect} onReplaceActiveTab={noopReplace} allContent={{}} onCreateNote={vi.fn()} />
+    )
+    fireEvent.click(screen.getByText('Note 50'))
+    expect(noopReplace).toHaveBeenCalledWith(entries[50])
+  })
+})