optimizations

interface/src/app/settings/TZ.tsx

@@ -1,8 +1,10 @@
+import { useMemo } from 'react';
+
 import { MenuItem } from '@mui/material';
 
 type TimeZones = Record<string, string>;
 
-export const TIME_ZONES: TimeZones = {
+export const TIME_ZONES: Readonly<TimeZones> = {
   'Africa/Abidjan': 'GMT0',
   'Africa/Accra': 'GMT0',
   'Africa/Addis_Ababa': 'EAT-3',
@@ -465,14 +467,33 @@ export const TIME_ZONES: TimeZones = {
   'Pacific/Wallis': 'UNK-12'
 };
 
+// Pre-compute sorted timezone labels for better performance
+export const TIME_ZONE_LABELS = Object.keys(TIME_ZONES).sort();
+
 export function selectedTimeZone(label: string, format: string) {
   return TIME_ZONES[label] === format ? label : undefined;
 }
 
-export function timeZoneSelectItems() {
-  return Object.keys(TIME_ZONES).map((label) => (
-    <MenuItem key={label} value={label}>
-      {label}
-    </MenuItem>
-  ));
+// Memoized version for use in components
+export function useTimeZoneSelectItems() {
+  return useMemo(
+    () =>
+      TIME_ZONE_LABELS.map((label) => (
+        <MenuItem key={label} value={label}>
+          {label}
+        </MenuItem>
+      )),
+    []
+  );
+}
+
+// Fallback export for backward compatibility - now memoized
+const precomputedTimeZoneItems = TIME_ZONE_LABELS.map((label) => (
+  <MenuItem key={label} value={label}>
+    {label}
+  </MenuItem>
+));
+
+export function timeZoneSelectItems() {
+  return precomputedTimeZoneItems;
 }