Add in-memory caching for online count, enable compression, and add staleTimes for router cache

src/app/api/online/count/route.ts

@@ -4,16 +4,16 @@
 // { count: 0 } (never 500) on DB failure.
 
 import { apiJson } from "@/lib/api";
+import { cached } from "@/lib/cache";
 import { prisma } from "@/lib/prisma";
 
 export const dynamic = "force-dynamic";
 
 export async function GET(_req: Request) {
   try {
-    const count = await prisma.user.count({
-      where: { online: "1" },
-    });
-
+    const count = await cached("online_count", 10_000, () =>
+      prisma.user.count({ where: { online: "1" } }),
+    );
     return apiJson({ count });
   } catch {
     return apiJson({ count: 0 });

src/app/layout.tsx

@@ -67,6 +67,8 @@ export default async function RootLayout({ children }: { children: ReactNode })
       <head>
         <meta name="theme-default-dark" content={String(defaultDark)} />
         <script src="/scripts/theme-init.js" />
+        <link rel="preconnect" href="https://www.habbo.com" />
+        <link rel="dns-prefetch" href="https://www.habbo.com" />
       </head>
       <body
         className="flex min-h-screen flex-col site-bg"

src/components/site-header.tsx

@@ -1,6 +1,7 @@
 import { getTranslations } from "next-intl/server";
 import Link from "next/link";
 import { auth } from "@/lib/auth";
+import { cached } from "@/lib/cache";
 import { prisma } from "@/lib/prisma";
 import { siteSettings } from "@/lib/services/site-settings";
 
@@ -15,7 +16,9 @@ export async function SiteHeader() {
 
   let online = 0;
   try {
-    online = await prisma.user.count({ where: { online: "1" } });
+    online = await cached("online_count", 10_000, () =>
+      prisma.user.count({ where: { online: "1" } }),
+    );
   } catch {
     online = 0;
   }

src/lib/cache.ts

@@ -0,0 +1,17 @@
+type CacheEntry<T> = { data: T; expiresAt: number };
+const store = new Map<string, CacheEntry<unknown>>();
+
+export function cached<T>(key: string, ttlMs: number, fn: () => Promise<T>): Promise<T> {
+  const existing = store.get(key);
+  if (existing && existing.expiresAt > Date.now()) {
+    return Promise.resolve(existing.data as T);
+  }
+  return fn().then((data) => {
+    store.set(key, { data, expiresAt: Date.now() + ttlMs });
+    return data;
+  });
+}
+
+export function bustCache(key: string): void {
+  store.delete(key);
+}