diff --git a/Dockerfile b/Dockerfile
index 1faeb0a..d9d7e22 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -34,6 +34,7 @@ FROM node:20-alpine AS production
 # Set environment
 ENV NODE_ENV=production
 ENV PORT=3000
+ENV NODE_OPTIONS="--max-old-space-size=2048 --expose-gc"
 
 WORKDIR /app
 
@@ -73,5 +74,5 @@ EXPOSE 2237/udp
 HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
   CMD wget --no-verbose --tries=1 --spider http://localhost:3000/api/health || exit 1
 
-# Start server with explicit heap limit (fail fast rather than slow OOM at 4GB)
-CMD ["node", "--max-old-space-size=1024", "server.js"]
+# Start server with explicit heap limit and GC access for periodic compaction
+CMD ["node", "--max-old-space-size=2048", "--expose-gc", "server.js"]
diff --git a/server.js b/server.js
index 6fa192e..65241be 100644
--- a/server.js
+++ b/server.js
@@ -895,7 +895,11 @@ function loadVisitorStats() {
         totalRequestsToday: data.today === new Date().toISOString().slice(0, 10) ? (data.totalRequestsToday || 0) : 0,
         allTimeVisitors: data.allTimeVisitors || 0,
         allTimeRequests: data.allTimeRequests || 0,
-        allTimeUniqueIPs: data.allTimeUniqueIPs || [],
+        // Reconstruct from geoIPCache keys (covers ~99% of IPs) + any legacy array
+        allTimeUniqueIPs: [...new Set([
+          ...(data.allTimeUniqueIPs || []),
+          ...Object.keys(data.geoIPCache || {})
+        ])],
         serverFirstStarted: data.serverFirstStarted || defaults.serverFirstStarted,
         lastDeployment: new Date().toISOString(),
         deploymentCount: (data.deploymentCount || 0) + 1,
@@ -925,12 +929,16 @@ function saveVisitorStats() {
       fs.mkdirSync(dir, { recursive: true });
     }
     
+    // Don't persist allTimeUniqueIPs array — it grows forever and can be
+    // reconstructed from geoIPCache keys on restart. Save memory.
     const data = {
       ...visitorStats,
+      allTimeUniqueIPs: undefined, // Exclude from JSON — reconstructed on load
       lastSaved: new Date().toISOString()
     };
     
-    fs.writeFileSync(STATS_FILE, JSON.stringify(data, null, 2));
+    // Use compact JSON (no pretty-print) to avoid multi-MB temporary strings
+    fs.writeFileSync(STATS_FILE, JSON.stringify(data));
     visitorStats.lastSaved = data.lastSaved; // Update in-memory too
     saveErrorCount = 0; // Reset on success
     // Only log occasionally to avoid spam
@@ -955,6 +963,10 @@ const visitorStats = loadVisitorStats();
 // Convert today's IPs to a Set for fast lookup
 const todayIPSet = new Set(visitorStats.uniqueIPsToday);
 const allTimeIPSet = new Set(visitorStats.allTimeUniqueIPs);
+const MAX_TRACKED_IPS = 100000; // Stop tracking individual IPs after this (just count)
+
+// Free the array — Set is the authoritative source now, array is no longer persisted
+visitorStats.allTimeUniqueIPs = [];
 
 // ============================================
 // GEO-IP COUNTRY RESOLUTION
@@ -998,8 +1010,11 @@ function queueGeoIPLookup(ip) {
  */
 function recordCountry(ip, countryCode) {
   if (!countryCode || countryCode === 'Unknown') return;
-  geoIPCache.set(ip, countryCode);
-  visitorStats.geoIPCache[ip] = countryCode;
+  // Only cache individual IP→country mappings up to the cap
+  if (geoIPCache.size < MAX_TRACKED_IPS || geoIPCache.has(ip)) {
+    geoIPCache.set(ip, countryCode);
+    visitorStats.geoIPCache[ip] = countryCode;
+  }
   
   // All-time stats
   visitorStats.countryStats[countryCode] = (visitorStats.countryStats[countryCode] || 0) + 1;
@@ -1332,8 +1347,10 @@ app.use((req, res, next) => {
     // Track all-time unique visitors
     const isNewAllTime = !allTimeIPSet.has(ip);
     if (isNewAllTime) {
-      allTimeIPSet.add(ip);
-      visitorStats.allTimeUniqueIPs.push(ip);
+      // Only track individual IPs up to the cap (prevents unbounded memory growth)
+      if (allTimeIPSet.size < MAX_TRACKED_IPS) {
+        allTimeIPSet.add(ip);
+      }
       visitorStats.allTimeVisitors++;
       queueGeoIPLookup(ip);
       logInfo(`[Stats] New visitor (#${visitorStats.uniqueIPsToday.length} today, #${visitorStats.allTimeVisitors} all-time) from ${ip.replace(/\d+$/, 'x')}`);
@@ -1370,9 +1387,23 @@ setInterval(() => {
     spotBufferEntries: pskMqtt.spotBuffer.size,
     spotBufferTotal: [...pskMqtt.spotBuffer.values()].reduce((n, b) => n + b.length, 0),
   };
-  console.log(`[Memory] RSS=${mb(mem.rss)}MB Heap=${mb(mem.heapUsed)}/${mb(mem.heapTotal)}MB External=${mb(mem.external)}MB | MQTT: ${mqttStats.sseClients} SSE clients, ${mqttStats.subscribedCalls} calls, ${mqttStats.recentSpotsTotal} recent spots (${mqttStats.recentSpotsEntries} entries), ${mqttStats.spotBufferTotal} buffered | GeoIP=${geoIPCache.size} CallLookup=${callsignLookupCache?.size || 0} MySpots=${mySpotsCache.size} AllTimeIPs=${allTimeIPSet.size}`);
+  console.log(`[Memory] RSS=${mb(mem.rss)}MB Heap=${mb(mem.heapUsed)}/${mb(mem.heapTotal)}MB External=${mb(mem.external)}MB | MQTT: ${mqttStats.sseClients} SSE clients, ${mqttStats.subscribedCalls} calls, ${mqttStats.recentSpotsTotal} recent spots (${mqttStats.recentSpotsEntries} entries), ${mqttStats.spotBufferTotal} buffered | GeoIP=${geoIPCache.size} CallLookup=${callsignLookupCache?.size || 0} MySpots=${mySpotsCache.size} AllTimeIPs=${allTimeIPSet.size} RBN=${rbnSpotsByDX?.size || 0}`);
 }, 15 * 60 * 1000);
 
+// Periodic GC compaction — helps V8 release fragmented old-space memory
+// Without this, long-running processes slowly accumulate unreclaimable heap
+setInterval(() => {
+  if (typeof global.gc === 'function') {
+    const before = process.memoryUsage().heapUsed;
+    global.gc();
+    const after = process.memoryUsage().heapUsed;
+    const freed = ((before - after) / 1024 / 1024).toFixed(1);
+    if (freed > 5) {
+      console.log(`[GC] Compaction freed ${freed}MB (${(before / 1024 / 1024).toFixed(0)}MB → ${(after / 1024 / 1024).toFixed(0)}MB)`);
+    }
+  }
+}, 30 * 60 * 1000); // Every 30 minutes
+
 // ============================================
 // AUTO UPDATE (GIT)
 // ============================================