diff --git a/otel-ui/src/components/TraceVisualization.tsx b/otel-ui/src/components/TraceVisualization.tsx
index 7528e42..4e872e3 100644
--- a/otel-ui/src/components/TraceVisualization.tsx
+++ b/otel-ui/src/components/TraceVisualization.tsx
@@ -1,4 +1,4 @@
-import { useMemo, useState, useRef, useEffect } from "react";
+import { useMemo, useState, useRef, useEffect, useDeferredValue } from "react";
 import { useVirtualizer } from "@tanstack/react-virtual";
 import {
   Sparkles,
@@ -54,6 +54,8 @@ export type ProcessedTrace = {
   endpoint: string;
 };
 
+const EMPTY_TRACES: TraceData[] = [];
+
 // Flattened item for virtualized tree rendering
 interface FlattenedSpanItem {
   span: ProcessedSpan;
@@ -96,14 +98,24 @@ const flattenSpanTree = (
   collapsedSet: Set<string>,
   traceMinTime: number,
   traceTotalRange: number,
-  depth = 0,
+  initialDepth = 0,
 ): FlattenedSpanItem[] => {
   const result: FlattenedSpanItem[] = [];
+  const pending: Array<{ span: ProcessedSpan; depth: number }> = [];
 
-  for (const span of nodes) {
-    const hasChildren = Boolean(span.children && span.children.length > 0);
+  for (let index = nodes.length - 1; index >= 0; index -= 1) {
+    pending.push({ span: nodes[index], depth: initialDepth });
+  }
+
+  // Avoid recursively spreading descendant arrays: deep parent/child chains
+  // otherwise copy the same nodes once per ancestor.
+  while (pending.length > 0) {
+    const current = pending.pop();
+    if (!current) break;
+    const { span, depth } = current;
+    const children = span.children ?? [];
+    const hasChildren = children.length > 0;
     const isCollapsed = collapsedSet.has(span.spanId);
-
     const offsetPercent =
       traceTotalRange === 0 ? 0 : ((span.startTime - traceMinTime) / traceTotalRange) * 100;
     const widthPercent =
@@ -118,16 +130,10 @@ const flattenSpanTree = (
       widthPercent: Math.max(0.5, Math.min(widthPercent, 100 - offsetPercent)),
     });
 
-    if (hasChildren && !isCollapsed && span.children) {
-      result.push(
-        ...flattenSpanTree(
-          span.children,
-          collapsedSet,
-          traceMinTime,
-          traceTotalRange,
-          depth + 1,
-        ),
-      );
+    if (hasChildren && !isCollapsed) {
+      for (let index = children.length - 1; index >= 0; index -= 1) {
+        pending.push({ span: children[index], depth: depth + 1 });
+      }
     }
   }
 
@@ -539,6 +545,7 @@ const VirtualizedSpanWaterfall = ({
   const [searchQuery, setSearchQuery] = useState("");
   const [errorsOnly, setErrorsOnly] = useState(false);
   const [minDurationMsFilter, setMinDurationMsFilter] = useState<number>(0);
+  const deferredSearchQuery = useDeferredValue(searchQuery);
   const parentRef = useRef<HTMLDivElement>(null);
 
   // Build tree
@@ -563,8 +570,8 @@ const VirtualizedSpanWaterfall = ({
         const durMs = item.span.duration / 1_000_000;
         if (durMs < minDurationMsFilter) return false;
       }
-      if (searchQuery.trim()) {
-        const query = searchQuery.toLowerCase().trim();
+      if (deferredSearchQuery.trim()) {
+        const query = deferredSearchQuery.toLowerCase().trim();
         const matchesName = item.span.name.toLowerCase().includes(query);
         const matchesService = item.span.service.toLowerCase().includes(query);
         const matchesAttrs = Object.values(item.span.formattedAttributes).some((v) =>
@@ -574,7 +581,7 @@ const VirtualizedSpanWaterfall = ({
       }
       return true;
     });
-  }, [flattenedItems, filterService, errorsOnly, minDurationMsFilter, searchQuery]);
+  }, [flattenedItems, filterService, errorsOnly, minDurationMsFilter, deferredSearchQuery]);
 
 
   // Virtualizer
@@ -1683,10 +1690,12 @@ export const processTraces = (
     ),
   );
 
-  const uniqueSpans = spanAccumulator.filter(
-    (span, index, arr) =>
-      arr.findIndex((candidate) => candidate.spanId === span.spanId) === index,
-  );
+  const seenSpanIds = new Set<string>();
+  const uniqueSpans = spanAccumulator.filter((span) => {
+    if (seenSpanIds.has(span.spanId)) return false;
+    seenSpanIds.add(span.spanId);
+    return true;
+  });
 
   const traceGroups = uniqueSpans.reduce<Record<string, ProcessedSpan[]>>((acc, span) => {
     if (!acc[span.traceId]) acc[span.traceId] = [];
@@ -1739,7 +1748,7 @@ export interface TraceVisualizationProps {
 }
 
 export const TraceVisualization = ({ traces }: TraceVisualizationProps) => {
-  const safeTraces = traces ?? [];
+  const safeTraces = traces ?? EMPTY_TRACES;
   const {
     logCountBySpanId,
     activeTraceId,
@@ -1756,6 +1765,7 @@ export const TraceVisualization = ({ traces }: TraceVisualizationProps) => {
  "recent" | "duration-desc" | "duration-asc" | "errors" | "spans"
   >("recent");
   const [groupByEndpoint, setGroupByEndpoint] = useState(false);
+  const deferredTraceSearchQuery = useDeferredValue(traceSearchQuery);
 
   const orderedTraces: ProcessedTrace[] = useMemo(
     () => processTraces(safeTraces, logCountBySpanId),
@@ -1774,8 +1784,8 @@ export const TraceVisualization = ({ traces }: TraceVisualizationProps) => {
         if (traceFilter === "errors" && !t.hasError) return false;
         if (traceFilter === "slow" && t.duration / 1_000_000 < 200) return false;
         if (traceServiceFilter !== "all" && !t.services.includes(traceServiceFilter)) return false;
-        if (traceSearchQuery.trim()) {
-          const q = traceSearchQuery.toLowerCase().trim();
+        if (deferredTraceSearchQuery.trim()) {
+          const q = deferredTraceSearchQuery.toLowerCase().trim();
           const matchName = t.name.toLowerCase().includes(q);
           const matchId = t.id.toLowerCase().includes(q);
           const matchService = t.services.some((s) => s.toLowerCase().includes(q));
@@ -1791,7 +1801,7 @@ export const TraceVisualization = ({ traces }: TraceVisualizationProps) => {
         if (traceSortBy === "spans") return b.spans.length - a.spans.length;
         return b.startTime - a.startTime; // recent
       });
-  }, [orderedTraces, traceFilter, traceServiceFilter, traceSearchQuery, traceSortBy]);
+  }, [orderedTraces, traceFilter, traceServiceFilter, deferredTraceSearchQuery, traceSortBy]);
 
   const groupCounts = useMemo(() => {
     const counts: Record<string, number> = {};