diff --git a/.Jules/bolt.md b/.Jules/bolt.md
index f02512d4..94e8748d 100644
--- a/.Jules/bolt.md
+++ b/.Jules/bolt.md
@@ -41,3 +41,7 @@ Action: Updated `collectItems` in `src/utils/whats-new-glance.ts` to iterate ove
 2026-09-08 - Zero-Allocation Reverse Array Scan for Chat Follow-up Prompts
 Learning: Dynamic shallow array copying and array reversal (`[...messages].reverse().find(...)`) on every UI update creates unnecessary temporary heap allocations and garbage collection overhead in client-side scripts. Replacing array copy/reverse with a reverse indexed `for` loop eliminates dynamic array allocations completely and stops scanning as soon as the first matching element is found.
 Action: Refactored `showFollowUps()` in `src/components/Chat.astro` to use an indexed reverse `for` loop.
+
+2026-09-19 - Pre-Computed Tabular Column Indexing & Zero-Allocation Date Slicing
+Learning: Performing repeated `columns.indexOf(key)` scans (12 times per response) when parsing PostHog HogQL API tabular arrays creates unnecessary O(N) array iteration overhead on edge Workers. Pre-building a `Record<string, number>` hashtable index map once converts column lookups into O(1) constant-time property reads. Additionally, replacing `date.toISOString().split('T')[0]` with `date.toISOString().slice(0, 10)` in date utilities extracts ISO date strings directly without intermediate string array allocation.
+Action: Pre-build column index maps for tabular API response parsers and use `date.toISOString().slice(0, 10)` for YYYY-MM-DD extraction in edge utility functions.
diff --git a/package-lock.json b/package-lock.json
index b332bbda..02c8cc32 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5167,9 +5167,10 @@
       }
     },
     "node_modules/devalue": {
-      "version": "5.9.0",
-      "resolved": "https://registry.npmjs.org/devalue/-/devalue-5.9.0.tgz",
-      "integrity": "sha512-RWrqdArjvPbsATEhOPUo6Wndc/iWnkWKlhIrdlF3zMMYo/c3CVtoaVAyLtWxz5h8nSlkHzxnzV2uLydPXmtF+A=="
+      "version": "5.9.1",
+      "resolved": "https://registry.npmjs.org/devalue/-/devalue-5.9.1.tgz",
+      "integrity": "sha512-+17vil3EVQRzvtDJSFuTWEb8XJRvXqAiV3qZyQWD398QeXUa6CxsUyMdD1fxzEhUrd4FojitFz7lhIHBTlV4fw==",
+      "license": "MIT"
     },
     "node_modules/devlop": {
       "version": "1.1.0",
diff --git a/package.json b/package.json
index 5070b267..ce5b4485 100644
--- a/package.json
+++ b/package.json
@@ -49,6 +49,7 @@
     "vitest": "^4.1.2"
   },
   "overrides": {
+    "devalue": "5.9.1",
     "brace-expansion": "5.0.9",
     "postcss": "8.5.26",
     "yaml": "2.8.3",
diff --git a/src/utils/github-releases.ts b/src/utils/github-releases.ts
index d2b6cb48..2a0dbb9f 100644
--- a/src/utils/github-releases.ts
+++ b/src/utils/github-releases.ts
@@ -176,7 +176,8 @@ export function formatReleaseDate(dateString: string | null): string {
     return 'Unknown date';
   }
 
-  return date.toISOString().split('T')[0];
+  // Extract YYYY-MM-DD date substring directly to avoid dynamic 2-element array allocation on edge runtimes
+  return date.toISOString().slice(0, 10);
 }
 
 /**
diff --git a/src/utils/visit-stats.ts b/src/utils/visit-stats.ts
index 17e005d0..e3767f81 100644
--- a/src/utils/visit-stats.ts
+++ b/src/utils/visit-stats.ts
@@ -45,18 +45,22 @@ function asIsoTimestamp(raw: unknown): string | null {
   return d.toISOString();
 }
 
+/**
+ * Extracts a column value from a row using either object property access or hashtable column index map.
+ * Replaces repeated O(N) array indexOf scans with O(1) constant-time property reads.
+ */
 function valueFromRow(
   row: unknown,
-  columns: string[] | undefined,
+  columnMap: Record<string, number> | undefined,
   key: string,
   index: number
 ): unknown {
   if (row && typeof row === 'object' && !Array.isArray(row) && key in row) {
     return (row as Record<string, unknown>)[key];
   }
-  if (Array.isArray(row) && columns) {
-    const colIndex = columns.indexOf(key);
-    if (colIndex >= 0) return row[colIndex];
+  if (Array.isArray(row) && columnMap) {
+    const colIndex = columnMap[key];
+    if (colIndex !== undefined) return row[colIndex];
   }
   if (Array.isArray(row)) return row[index];
   return undefined;
@@ -76,26 +80,31 @@ export function parseVisitGlance(payload: unknown): VisitGlance | null {
   if (!Array.isArray(results) || results.length === 0) return null;
 
   const columns = (payload as { columns?: unknown }).columns;
-  const columnNames = Array.isArray(columns)
-    ? columns.filter((c): c is string => typeof c === 'string')
-    : undefined;
+  let columnMap: Record<string, number> | undefined;
+  if (Array.isArray(columns)) {
+    columnMap = {};
+    for (let i = 0; i < columns.length; i++) {
+      const col = columns[i];
+      if (typeof col === 'string') {
+        columnMap[col] = i;
+      }
+    }
+  }
 
   const row = results[0];
-  const pageviews = asFiniteNumber(valueFromRow(row, columnNames, 'pageviews', 0));
-  const uniqueVisitors = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors', 1));
-  const firstSeen = asIsoTimestamp(valueFromRow(row, columnNames, 'first_seen', 2));
-  const pageviews7d = asFiniteNumber(valueFromRow(row, columnNames, 'pageviews_7d', 3));
-  const uniqueVisitors7d = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_7d', 4));
-  const unique1d = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_1d', 5));
-  const unique1dPrev = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_1d_prev', 6));
-  const unique7dPrev = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_7d_prev', 7));
-  const unique30d = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_30d', 8));
-  const unique30dPrev = asFiniteNumber(
-    valueFromRow(row, columnNames, 'unique_visitors_30d_prev', 9)
-  );
-  const unique365d = asFiniteNumber(valueFromRow(row, columnNames, 'unique_visitors_365d', 10));
+  const pageviews = asFiniteNumber(valueFromRow(row, columnMap, 'pageviews', 0));
+  const uniqueVisitors = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors', 1));
+  const firstSeen = asIsoTimestamp(valueFromRow(row, columnMap, 'first_seen', 2));
+  const pageviews7d = asFiniteNumber(valueFromRow(row, columnMap, 'pageviews_7d', 3));
+  const uniqueVisitors7d = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_7d', 4));
+  const unique1d = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_1d', 5));
+  const unique1dPrev = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_1d_prev', 6));
+  const unique7dPrev = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_7d_prev', 7));
+  const unique30d = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_30d', 8));
+  const unique30dPrev = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_30d_prev', 9));
+  const unique365d = asFiniteNumber(valueFromRow(row, columnMap, 'unique_visitors_365d', 10));
   const unique365dPrev = asFiniteNumber(
-    valueFromRow(row, columnNames, 'unique_visitors_365d_prev', 11)
+    valueFromRow(row, columnMap, 'unique_visitors_365d_prev', 11)
   );
 
   if (