diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 176c7e3cb..0a1c00f3d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,10 +13,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 11
-      uses: actions/setup-java@v1
+    - name: Set up JDK 16
+      uses: actions/setup-java@v2
       with:
-        java-version: 11
+        distribution: 'adopt'
+        java-version: 16
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
     - name: Setup gradle cache
diff --git a/src/main/java/net/minestom/server/UpdateManager.java b/src/main/java/net/minestom/server/UpdateManager.java
index afe43c11d..f337a0a1b 100644
--- a/src/main/java/net/minestom/server/UpdateManager.java
+++ b/src/main/java/net/minestom/server/UpdateManager.java
@@ -15,6 +15,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.List;
 import java.util.Queue;
 import java.util.concurrent.*;
+import java.util.concurrent.locks.LockSupport;
 import java.util.function.Consumer;
 import java.util.function.LongConsumer;
 
@@ -25,9 +26,6 @@ import java.util.function.LongConsumer;
  */
 public final class UpdateManager {
 
-    private final ScheduledExecutorService updateExecutionService = Executors.newSingleThreadScheduledExecutor(r ->
-            new Thread(r, MinecraftServer.THREAD_NAME_TICK_SCHEDULER));
-
     private volatile boolean stopRequested;
 
     // TODO make configurable
@@ -49,54 +47,52 @@ public final class UpdateManager {
     protected void start() {
         final ConnectionManager connectionManager = MinecraftServer.getConnectionManager();
 
-        updateExecutionService.scheduleAtFixedRate(() -> {
-            try {
-                if (stopRequested) {
-                    updateExecutionService.shutdown();
-                    return;
+        new Thread(() -> {
+            while (!stopRequested) {
+                try {
+                    long currentTime = System.nanoTime();
+                    final long tickStart = System.currentTimeMillis();
+
+                    // Tick start callbacks
+                    doTickCallback(tickStartCallbacks, tickStart);
+
+                    // Waiting players update (newly connected clients waiting to get into the server)
+                    connectionManager.updateWaitingPlayers();
+
+                    // Keep Alive Handling
+                    connectionManager.handleKeepAlive(tickStart);
+
+                    // Server tick (chunks/entities)
+                    serverTick(tickStart);
+
+                    // the time that the tick took in nanoseconds
+                    final long tickTime = System.nanoTime() - currentTime;
+
+                    // Tick end callbacks
+                    doTickCallback(tickEndCallbacks, tickTime);
+
+                    // Monitoring
+                    if (!tickMonitors.isEmpty()) {
+                        final double acquisitionTimeMs = Acquirable.getAcquiringTime() / 1e6D;
+                        final double tickTimeMs = tickTime / 1e6D;
+                        final TickMonitor tickMonitor = new TickMonitor(tickTimeMs, acquisitionTimeMs);
+                        this.tickMonitors.forEach(consumer -> consumer.accept(tickMonitor));
+                        Acquirable.resetAcquiringTime();
+                    }
+
+                    // Flush all waiting packets
+                    AsyncUtils.runAsync(() -> connectionManager.getOnlinePlayers().parallelStream()
+                            .filter(player -> player.getPlayerConnection() instanceof NettyPlayerConnection)
+                            .map(player -> (NettyPlayerConnection) player.getPlayerConnection())
+                            .forEach(NettyPlayerConnection::flush));
+
+                    // Disable thread until next tick
+                    LockSupport.parkNanos((long) ((MinecraftServer.TICK_MS * 1e6) - tickTime));
+                } catch (Exception e) {
+                    MinecraftServer.getExceptionManager().handleException(e);
                 }
-
-                long currentTime = System.nanoTime();
-                final long tickStart = System.currentTimeMillis();
-
-                // Tick start callbacks
-                doTickCallback(tickStartCallbacks, tickStart);
-
-                // Waiting players update (newly connected clients waiting to get into the server)
-                connectionManager.updateWaitingPlayers();
-
-                // Keep Alive Handling
-                connectionManager.handleKeepAlive(tickStart);
-
-                // Server tick (chunks/entities)
-                serverTick(tickStart);
-
-                // the time that the tick took in nanoseconds
-                final long tickTime = System.nanoTime() - currentTime;
-
-                // Tick end callbacks
-                doTickCallback(tickEndCallbacks, tickTime);
-
-                // Monitoring
-                if (!tickMonitors.isEmpty()) {
-                    final double acquisitionTimeMs = Acquirable.getAcquiringTime() / 1e6D;
-                    final double tickTimeMs = tickTime / 1e6D;
-                    final TickMonitor tickMonitor = new TickMonitor(tickTimeMs, acquisitionTimeMs);
-                    this.tickMonitors.forEach(consumer -> consumer.accept(tickMonitor));
-
-                    Acquirable.resetAcquiringTime();
-                }
-
-                // Flush all waiting packets
-                AsyncUtils.runAsync(() -> connectionManager.getOnlinePlayers().parallelStream()
-                        .filter(player -> player.getPlayerConnection() instanceof NettyPlayerConnection)
-                        .map(player -> (NettyPlayerConnection) player.getPlayerConnection())
-                        .forEach(NettyPlayerConnection::flush));
-
-            } catch (Exception e) {
-                MinecraftServer.getExceptionManager().handleException(e);
             }
-        }, 0, MinecraftServer.TICK_MS, TimeUnit.MILLISECONDS);
+        }, MinecraftServer.THREAD_NAME_TICK_SCHEDULER).start();
     }
 
     /**
diff --git a/src/main/java/net/minestom/server/network/packet/server/play/ExplosionPacket.java b/src/main/java/net/minestom/server/network/packet/server/play/ExplosionPacket.java
index acd4fee22..8605e993c 100644
--- a/src/main/java/net/minestom/server/network/packet/server/play/ExplosionPacket.java
+++ b/src/main/java/net/minestom/server/network/packet/server/play/ExplosionPacket.java
@@ -36,7 +36,7 @@ public class ExplosionPacket implements ServerPacket {
         y = reader.readFloat();
         z = reader.readFloat();
         radius = reader.readFloat();
-        int recordCount = reader.readInt() * 3;
+        int recordCount = reader.readVarInt() * 3;
         records = reader.readBytes(recordCount);
         playerMotionX = reader.readFloat();
         playerMotionY = reader.readFloat();
diff --git a/src/main/java/net/minestom/server/network/packet/server/play/MapDataPacket.java b/src/main/java/net/minestom/server/network/packet/server/play/MapDataPacket.java
index 5d1386e07..bd9d87295 100644
--- a/src/main/java/net/minestom/server/network/packet/server/play/MapDataPacket.java
+++ b/src/main/java/net/minestom/server/network/packet/server/play/MapDataPacket.java
@@ -73,11 +73,15 @@ public class MapDataPacket implements ComponentHoldingServerPacket {
         locked = reader.readBoolean();
         trackingPosition = reader.readBoolean();
 
-        int iconCount = reader.readVarInt();
-        icons = new Icon[iconCount];
-        for (int i = 0; i < iconCount; i++) {
-            icons[i] = new Icon();
-            icons[i].read(reader);
+        if (trackingPosition) {
+            int iconCount = reader.readVarInt();
+            icons = new Icon[iconCount];
+            for (int i = 0; i < iconCount; i++) {
+                icons[i] = new Icon();
+                icons[i].read(reader);
+            }
+        } else {
+            icons = new Icon[0];
         }
 
         columns = reader.readByte();