diff --git a/apps/desktop/src/components/sidebar/ConnectionTree.vue b/apps/desktop/src/components/sidebar/ConnectionTree.vue
index 86dfafc0d..4573c759f 100644
--- a/apps/desktop/src/components/sidebar/ConnectionTree.vue
+++ b/apps/desktop/src/components/sidebar/ConnectionTree.vue
@@ -19,6 +19,7 @@ import { activeTabSidebarTarget, findSidebarNodeForActiveTab, findSidebarNodeFor
 import { findLoadedTableTargetForCandidate, queryContextTargetFromCandidate, queryCursorTableCandidate, type QueryCursorTableCandidate } from "@/lib/sql/queryCursorTableTarget";
 import { SIDEBAR_TREE_ROW_HEIGHT, SIDEBAR_TREE_PRERENDER_COUNT, SIDEBAR_TREE_SCROLL_BUFFER, flattenTree, shouldVirtualizeFlatTree, type FlatTreeNode } from "@/composables/useFlatTree";
 import { sidebarTreeContextKey } from "@/lib/sidebar/sidebarTreeContext";
+import { createSidebarPasteHandlerRegistry } from "@/lib/sidebar/sidebarPasteHandlerRegistry";
 import { insertSidebarTableSearchControls, isSidebarTableSearchControlNode } from "@/lib/sidebar/sidebarTableSearchControl";
 import TreeItem from "./TreeItem.vue";
 import { RecycleScroller } from "vue-virtual-scroller";
@@ -520,6 +521,8 @@ function onSidebarScrollbarThumbPointerDown(event: PointerEvent) {
   window.addEventListener("pointercancel", stopSidebarScrollbarDrag);
 }
 
+const pasteHandlerRegistry = createSidebarPasteHandlerRegistry();
+
 provide(sidebarTreeContextKey, {
   getVisibleNodes: () => selectableVisibleNodes.value,
   getVisibleNodeIndex: (id: string) => selectableVisibleNodeIndexById.value.get(id) ?? -1,
@@ -528,6 +531,7 @@ provide(sidebarTreeContextKey, {
     store.setSidebarTableSearchQuery(parentNodeId, query);
     scheduleSidebarTableSearchRefresh(parentNodeId, { restoreFocus: true });
   },
+  registerPasteHandler: pasteHandlerRegistry.register,
 });
 
 const pendingRenameGroupId = ref<string | null>(null);
@@ -1032,8 +1036,8 @@ function requestSelectedSidebarPaste(): boolean {
     return true;
   }
   if (clipboard?.kind !== "table-copy" || clipboard.tables.length === 0 || !selectedNodeId) return false;
-  window.dispatchEvent(new CustomEvent("dbx:sidebar-request-paste-table", { detail: { nodeId: selectedNodeId } }));
-  return true;
+
+  return pasteHandlerRegistry.request(selectedNodeId);
 }
 
 onMounted(() => {
diff --git a/apps/desktop/src/components/sidebar/TreeItem.vue b/apps/desktop/src/components/sidebar/TreeItem.vue
index 355807744..9d4cfd75d 100644
--- a/apps/desktop/src/components/sidebar/TreeItem.vue
+++ b/apps/desktop/src/components/sidebar/TreeItem.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref, computed, nextTick, watch, onMounted, onBeforeUnmount, inject, type Component } from "vue";
+import { ref, computed, nextTick, watch, onBeforeUnmount, inject, type Component } from "vue";
 import { useSqlHighlighter } from "@/composables/useSqlHighlighter";
 import { useI18n } from "vue-i18n";
 import { translateBackendError } from "@/i18n/backend-errors";
@@ -227,18 +227,22 @@ function scheduleLabelOverflowMeasure() {
   });
 }
 
-function observeLabelOverflow() {
-  labelResizeObserver?.disconnect();
-  labelResizeObserver = null;
+function handleMouseEnter() {
   if (!shouldMeasureLabelOverflow()) {
     labelOverflowing.value = false;
     return;
   }
-  if (typeof ResizeObserver !== "undefined" && labelRef.value) {
+  updateLabelOverflow();
+  if (typeof ResizeObserver !== "undefined" && labelRef.value && !labelResizeObserver) {
     labelResizeObserver = new ResizeObserver(scheduleLabelOverflowMeasure);
     labelResizeObserver.observe(labelRef.value);
   }
-  scheduleLabelOverflowMeasure();
+}
+
+function handleMouseLeave() {
+  labelResizeObserver?.disconnect();
+  labelResizeObserver = null;
+  cancelLabelOverflowMeasure();
 }
 const connectionStore = useConnectionStore();
 const queryStore = useQueryStore();
@@ -992,12 +996,6 @@ function requestPasteTreeClipboard(): boolean {
   return true;
 }
 
-function onSidebarRequestPasteTable(event: Event) {
-  const nodeId = (event as CustomEvent<{ nodeId?: string }>).detail?.nodeId;
-  if (nodeId !== props.node.id) return;
-  requestPasteTreeClipboard();
-}
-
 function requestRefreshSelectedNode(): boolean {
   if (!canRefreshTreeNodeShortcut()) return false;
   void refresh();
@@ -1299,6 +1297,12 @@ async function openData() {
   queryStore.setExecutingWithId(tabId, openDataId);
   logPhase("state-prepared", { tabId });
 
+  // Yield to Vue's scheduler so the new tab becomes visible in the UI (tab
+  // bar activates, content area switches) before the first blocking network
+  // call. Without this the entire openData flow runs synchronously before the
+  // browser paints, making the UI feel frozen on each table click.
+  await nextTick();
+
   // Helper to check if this openData call is still active (not superseded by a newer click)
   const isActive = () => queryStore.tabs.find((t) => t.id === tabId)?.executionId === openDataId;
   const isCurrentDataTab = () => {
@@ -4180,7 +4184,7 @@ const isConnected = computed(() => props.node.type === "connection" && !!props.n
 const isConnecting = computed(() => props.node.type === "connection" && !!props.node.connectionId && connectionStore.connectingIds.has(props.node.connectionId));
 const isConnectionReadonly = computed(() => props.node.type === "connection" && !!props.node.connectionId && (connectionStore.getConfig(props.node.connectionId)?.read_only ?? false));
 const isOpenedDatabase = computed(() => isSidebarDatabaseOpened(props.node, connectionStore.isTreeNodeChildrenLoaded));
-const showsDatabaseOpenIndicator = computed(() => props.node.type === "database" && (isOpenedDatabase.value || (!!props.node.connectionId && props.node.database != null && queryStore.isDatabaseOpen(props.node.connectionId, props.node.database))));
+const showsDatabaseOpenIndicator = computed(() => props.node.type === "database" && (isOpenedDatabase.value || (!!props.node.connectionId && props.node.database != null && queryStore.openDatabaseKeys.has(`${props.node.connectionId}\x00${props.node.database}`))));
 const canCloseDatabaseConnection = computed(() => canCloseSidebarDatabaseConnection(props.node, connectionStore.isTreeNodeChildrenLoaded));
 const nodeIconClass = computed(() => {
   const infoClass = getIconInfo(props.node)?.colorClass;
@@ -4222,7 +4226,7 @@ const connectionColor = computed(() => {
 });
 const isActiveConnectionScope = computed(() => !!props.node.connectionId && connectionStore.activeConnectionId === props.node.connectionId);
 const isSelected = computed(() => connectionStore.selectedTreeNodeId === props.node.id);
-const isMultiSelected = computed(() => connectionStore.selectedTreeNodeIds.includes(props.node.id));
+const isMultiSelected = computed(() => connectionStore.selectedTreeNodeIdsSet.has(props.node.id));
 const isTreeRowSelected = computed(() => isSelected.value || isMultiSelected.value);
 const usesSelectionSetHighlight = computed(() => connectionStore.connectionMultiSelectActive || connectionStore.selectedTreeNodeIds.length > 1);
 const rowStyle = computed(() => {
@@ -4307,14 +4311,6 @@ watch(
   { immediate: true },
 );
 
-watch(
-  [() => props.node.id, () => visibleLabel(props.node), () => usesFullWidthLabel.value, () => detailTooltip.value?.rows.length ?? 0, isRenamingGroup],
-  () => {
-    nextTick(observeLabelOverflow);
-  },
-  { flush: "post", immediate: true },
-);
-
 function finishRenameGroup() {
   // Guard against double invocation: pressing Enter sets isRenamingGroup=false
   // and unmounts the input, which then fires @blur -> finishRenameGroup again.
@@ -4545,21 +4541,23 @@ function onRowMouseDown(event: MouseEvent) {
   }
 }
 
-onMounted(() => {
-  observeLabelOverflow();
-  window.addEventListener("dbx:sidebar-request-paste-table", onSidebarRequestPasteTable);
-});
+// RecycleScroller reuses mounted TreeItem instances for different nodes, so the
+// handler must follow the reactive node id rather than component mount lifetime.
+const stopPasteHandlerRegistration = watch(
+  () => props.node.id,
+  (nodeId, _previousNodeId, onCleanup) => {
+    const unregister = sidebarTreeContext?.registerPasteHandler?.(nodeId, requestPasteTreeClipboard);
+    if (unregister) onCleanup(unregister);
+  },
+  { immediate: true },
+);
 
 onBeforeUnmount(() => {
-  labelResizeObserver?.disconnect();
-  labelResizeObserver = null;
-  cancelLabelOverflowMeasure();
-  window.removeEventListener("dbx:sidebar-request-paste-table", onSidebarRequestPasteTable);
+  handleMouseLeave();
+  stopPasteHandlerRegistration();
   finishTableReferenceDrag();
 });
 
-// ---- CustomContextMenu ----
-
 const shortcutCopyName = computed(() => settingsStore.editorSettings.shortcuts.copySidebarSelection);
 const shortcutEditConnection = computed(() => settingsStore.editorSettings.shortcuts.editSidebarConnection);
 const shortcutRename = "F2";
@@ -5322,7 +5320,11 @@ function treeItemMenuItems(): ContextMenuItem[] {
           @keydown="onKeydown"
           @mousedown="onRowMouseDown"
           @mousemove="isDropTarget ? updateTarget($event, node.id, node.type) : undefined"
-          @mouseleave="clearTarget(node.id)"
+          @mouseenter="handleMouseEnter"
+          @mouseleave="
+            clearTarget(node.id);
+            handleMouseLeave();
+          "
         >
           <div v-if="showDropBefore" class="absolute right-2 top-0 h-0.5 bg-primary rounded-full pointer-events-none" :style="{ left: paddingLeft }" />
           <div v-if="showDropAfter" class="absolute right-2 bottom-0 h-0.5 bg-primary rounded-full pointer-events-none" :style="{ left: paddingLeft }" />
diff --git a/apps/desktop/src/lib/dataGrid/canvasDataGridRenderer.ts b/apps/desktop/src/lib/dataGrid/canvasDataGridRenderer.ts
index f145dd007..7f8ab5440 100644
--- a/apps/desktop/src/lib/dataGrid/canvasDataGridRenderer.ts
+++ b/apps/desktop/src/lib/dataGrid/canvasDataGridRenderer.ts
@@ -381,16 +381,14 @@ export function drawCanvasDataGrid(options: DrawCanvasDataGridOptions) {
       ctx.font = value === null ? italicFont : tabularFont;
       setCanvasNumericVariant(ctx, value === null ? "normal" : "tabular-nums");
       const textLeft = alignCanvasPixel(drawX + 12, dpr);
-      const paddedMaxWidth = Math.max(0, drawX + colWidth - textLeft - 12);
+      const cellMaxWidth = Math.max(0, colWidth - 24);
       const isEditingThisCell = editingCell?.rowId === item.id && editingCell.col === actualColIdx;
       const rawDisplayText = item.isDraft && value === null ? (draftCellPlaceholder ?? "") : formatCell(value, actualColIdx);
       const displayText = isEditingThisCell ? "" : firstLineCellDisplayValue(rawDisplayText);
-      const needsTruncation = ctx.measureText(displayText).width > paddedMaxWidth;
-      const textMaxWidth = needsTruncation ? Math.max(0, drawX + colWidth - textLeft) : paddedMaxWidth;
-      const text = isEditingThisCell ? displayText : fitCanvasText(ctx, displayText, textMaxWidth - 12);
+      const text = isEditingThisCell ? displayText : fitCanvasText(ctx, displayText, cellMaxWidth);
       ctx.fillText(text, textLeft, textY);
       if (item.isDeleted && text) {
-        const textWidth = Math.min(ctx.measureText(text).width, textMaxWidth);
+        const textWidth = ctx.measureText(text).width;
         ctx.strokeStyle = theme.foreground;
         ctx.beginPath();
         ctx.moveTo(textLeft, textY);
diff --git a/apps/desktop/src/lib/sidebar/sidebarPasteHandlerRegistry.ts b/apps/desktop/src/lib/sidebar/sidebarPasteHandlerRegistry.ts
new file mode 100644
index 000000000..870761cf9
--- /dev/null
+++ b/apps/desktop/src/lib/sidebar/sidebarPasteHandlerRegistry.ts
@@ -0,0 +1,40 @@
+export type SidebarPasteHandler = () => void;
+
+export interface SidebarPasteHandlerRegistry {
+  register: (nodeId: string, handler: SidebarPasteHandler) => () => void;
+  request: (nodeId: string) => boolean;
+}
+
+export function createSidebarPasteHandlerRegistry(): SidebarPasteHandlerRegistry {
+  const handlersByNodeId = new Map<string, Set<SidebarPasteHandler>>();
+
+  function register(nodeId: string, handler: SidebarPasteHandler) {
+    let handlers = handlersByNodeId.get(nodeId);
+    if (!handlers) {
+      handlers = new Set();
+      handlersByNodeId.set(nodeId, handlers);
+    }
+    handlers.add(handler);
+
+    return () => {
+      const currentHandlers = handlersByNodeId.get(nodeId);
+      if (!currentHandlers) return;
+      currentHandlers.delete(handler);
+      if (currentHandlers.size === 0) handlersByNodeId.delete(nodeId);
+    };
+  }
+
+  function request(nodeId: string): boolean {
+    const handlers = handlersByNodeId.get(nodeId);
+    if (!handlers?.size) return false;
+
+    // The sticky database row may duplicate a virtualized row. Prefer the most
+    // recently registered live instance while keeping older owners as fallback.
+    let activeHandler: SidebarPasteHandler | undefined;
+    for (const handler of handlers) activeHandler = handler;
+    activeHandler?.();
+    return true;
+  }
+
+  return { register, request };
+}
diff --git a/apps/desktop/src/lib/sidebar/sidebarTreeContext.ts b/apps/desktop/src/lib/sidebar/sidebarTreeContext.ts
index db13eb331..bda8058fe 100644
--- a/apps/desktop/src/lib/sidebar/sidebarTreeContext.ts
+++ b/apps/desktop/src/lib/sidebar/sidebarTreeContext.ts
@@ -5,6 +5,7 @@ export interface SidebarTreeContext {
   getVisibleNodes: () => TreeNode[];
   getVisibleNodeIndex: (id: string) => number;
   setTableSearchQuery?: (parentNodeId: string, query: string) => void;
+  registerPasteHandler?: (nodeId: string, callback: () => void) => () => void;
 }
 
 export const sidebarTreeContextKey: InjectionKey<SidebarTreeContext> = Symbol("sidebar-tree-context");
diff --git a/apps/desktop/src/stores/connectionStore.ts b/apps/desktop/src/stores/connectionStore.ts
index 1a12c05ab..2e82fdd9d 100644
--- a/apps/desktop/src/stores/connectionStore.ts
+++ b/apps/desktop/src/stores/connectionStore.ts
@@ -218,6 +218,10 @@ export const useConnectionStore = defineStore("connection", () => {
   const activeConnectionId = ref<string | null>(localStorage.getItem(ACTIVE_CONNECTION_STORAGE_KEY));
   const selectedTreeNodeId = ref<string | null>(null);
   const selectedTreeNodeIds = ref<string[]>([]);
+  // O(1) membership set — rebuilds only when selectedTreeNodeIds changes.
+  // Avoids O(N) Array.includes() in every visible TreeItem's isMultiSelected
+  // computed during scrolling and selection changes.
+  const selectedTreeNodeIdsSet = computed(() => new Set(selectedTreeNodeIds.value));
   const treeSelectionAnchorId = ref<string | null>(null);
   const connectionMultiSelectActive = ref(false);
   const treeClipboard = ref<TreeClipboard | null>(null);
@@ -5062,6 +5066,7 @@ export const useConnectionStore = defineStore("connection", () => {
     activeConnectionId,
     selectedTreeNodeId,
     selectedTreeNodeIds,
+    selectedTreeNodeIdsSet,
     treeSelectionAnchorId,
     connectionMultiSelectActive,
     treeClipboard,
diff --git a/apps/desktop/src/stores/queryStore.ts b/apps/desktop/src/stores/queryStore.ts
index 6f0500d3f..741886a3b 100644
--- a/apps/desktop/src/stores/queryStore.ts
+++ b/apps/desktop/src/stores/queryStore.ts
@@ -326,6 +326,21 @@ export const useQueryStore = defineStore("query", () => {
   const t = getI18nT();
   const settingsStore = useSettingsStore();
   const tabs = ref<QueryTab[]>([]);
+  // A stable Set of "connectionId\x00database" keys. Computed only from the
+  // minimal tab identity fields so that it does NOT invalidate when other
+  // properties change (isExecuting, result, sql, tableMeta...). Previously
+  // isDatabaseOpen() called tabs.value.some() which tracked the full reactive
+  // array — every mutation during openData() forced all database-type sidebar
+  // TreeItems to recompute showsDatabaseOpenIndicator.
+  const openDatabaseKeys = computed(() => {
+    const keys = new Set<string>();
+    for (const tab of tabs.value) {
+      if (tab.connectionId && tab.database != null) {
+        keys.add(`${tab.connectionId}\x00${tab.database}`);
+      }
+    }
+    return keys;
+  });
   const activeTabId = ref<string | null>(null);
   const isOpenTabsLoaded = ref(false);
   const activeTabHistory = ref<string[]>([]);
@@ -1665,7 +1680,7 @@ export const useQueryStore = defineStore("query", () => {
   }
 
   function isDatabaseOpen(connectionId: string, database: string) {
-    return tabs.value.some((tab) => tab.connectionId === connectionId && tab.database === database);
+    return openDatabaseKeys.value.has(`${connectionId}\x00${database}`);
   }
 
   function rollbackTabsWhere(predicate: (tab: QueryTab) => boolean, options?: { resetAutoCommit?: boolean }) {
@@ -3776,6 +3791,7 @@ export const useQueryStore = defineStore("query", () => {
     releaseConnectionTabs,
     releaseDatabaseTabs,
     isDatabaseOpen,
+    openDatabaseKeys,
     rollbackConnectionTransactions,
     rollbackDatabaseTransactions,
     updateSql,
diff --git a/packages/app-tests/sidebarPasteHandlerRegistry.test.ts b/packages/app-tests/sidebarPasteHandlerRegistry.test.ts
new file mode 100644
index 000000000..56a38c3eb
--- /dev/null
+++ b/packages/app-tests/sidebarPasteHandlerRegistry.test.ts
@@ -0,0 +1,35 @@
+import { strict as assert } from "node:assert";
+import { test } from "vitest";
+import { createSidebarPasteHandlerRegistry } from "../../apps/desktop/src/lib/sidebar/sidebarPasteHandlerRegistry.ts";
+
+test("unregistering one duplicate owner keeps the other handler active", () => {
+  const registry = createSidebarPasteHandlerRegistry();
+  const calls: string[] = [];
+  const unregisterVirtualRow = registry.register("database-1", () => calls.push("virtual"));
+  const unregisterStickyRow = registry.register("database-1", () => calls.push("sticky"));
+
+  assert.equal(registry.request("database-1"), true);
+  assert.deepEqual(calls, ["sticky"]);
+
+  unregisterStickyRow();
+  assert.equal(registry.request("database-1"), true);
+  assert.deepEqual(calls, ["sticky", "virtual"]);
+
+  unregisterVirtualRow();
+  assert.equal(registry.request("database-1"), false);
+});
+
+test("recycled row cleanup removes only its previous node registration", () => {
+  const registry = createSidebarPasteHandlerRegistry();
+  const calls: string[] = [];
+  const unregisterFirstNode = registry.register("table-1", () => calls.push("first"));
+
+  unregisterFirstNode();
+  const unregisterSecondNode = registry.register("table-2", () => calls.push("second"));
+
+  assert.equal(registry.request("table-1"), false);
+  assert.equal(registry.request("table-2"), true);
+  assert.deepEqual(calls, ["second"]);
+
+  unregisterSecondNode();
+});