Make liquid flow checking for regions optional.

src/main/java/com/sk89q/worldguard/bukkit/WorldConfiguration.java

@@ -130,6 +130,7 @@ public class WorldConfiguration {
     public boolean disableMobDamage;
     public boolean useRegions;
     public boolean highFreqFlags;
+    public boolean checkLiquidFlow;
     public int regionWand;
     public Set<EntityType> blockCreatureSpawn;
     public boolean allowTamedSpawns;
@@ -415,6 +416,7 @@ private void loadConfiguration() {
         regionInvinciblityRemovesMobs = getBoolean("regions.invincibility-removes-mobs", false);
         explosionFlagCancellation = getBoolean("regions.explosion-flags-block-entity-damage", true);
         highFreqFlags = getBoolean("regions.high-frequency-flags", false);
+        checkLiquidFlow = getBoolean("regions.protect-against-liquid-flow", false);
         regionWand = getInt("regions.wand", 334);
         maxClaimVolume = getInt("regions.max-claim-volume", 30000);
         claimOnlyInsideExistingRegions = getBoolean("regions.claim-only-inside-existing-regions", false);

src/main/java/com/sk89q/worldguard/bukkit/listener/EventAbstractionListener.java

@@ -20,6 +20,7 @@
 package com.sk89q.worldguard.bukkit.listener;
 
 import com.google.common.collect.Lists;
+import com.sk89q.worldguard.bukkit.WorldConfiguration;
 import com.sk89q.worldguard.bukkit.WorldGuardPlugin;
 import com.sk89q.worldguard.bukkit.cause.Cause;
 import com.sk89q.worldguard.bukkit.event.block.BreakBlockEvent;
@@ -51,7 +52,6 @@
 import org.bukkit.event.Event;
 import org.bukkit.event.Event.Result;
 import org.bukkit.event.EventHandler;
-import org.bukkit.event.Listener;
 import org.bukkit.event.block.Action;
 import org.bukkit.event.block.BlockBreakEvent;
 import org.bukkit.event.block.BlockBurnEvent;
@@ -108,7 +108,7 @@
 import static com.sk89q.worldguard.bukkit.util.Materials.isBlockModifiedOnClick;
 import static com.sk89q.worldguard.bukkit.util.Materials.isItemAppliedToBlock;
 
-public class EventAbstractionListener implements Listener {
+public class EventAbstractionListener extends AbstractListener {
 
     /**
      * Abstract {@link BlockFromToEvent}s into break and place events.
@@ -116,14 +116,17 @@ public class EventAbstractionListener implements Listener {
      */
     public static final boolean ABSTRACT_FROM_TO_EVENTS = false;
 
-    private final WorldGuardPlugin plugin;
+    /**
-
+     * Construct the listener.
+     *
+     * @param plugin an instance of WorldGuardPlugin
+     */
     public EventAbstractionListener(WorldGuardPlugin plugin) {
-        this.plugin = plugin;
+        super(plugin);
     }
 
     public void registerEvents() {
-        plugin.getServer().getPluginManager().registerEvents(this, plugin);
+        getPlugin().getServer().getPluginManager().registerEvents(this, getPlugin());
     }
 
     //-------------------------------------------------------------------------
@@ -382,6 +385,14 @@ public void onPlayerBucketFill(PlayerBucketFillEvent event) {
 
     @EventHandler
     public void onBlockFromTo(BlockFromToEvent event) {
+        WorldConfiguration config = getWorldConfig(event.getBlock().getWorld());
+
+        // This only applies to regions but nothing else cares about high
+        // frequency events at the moment
+        if (!config.useRegions || (!config.highFreqFlags && !config.checkLiquidFlow)) {
+            return;
+        }
+
         Block from = event.getBlock();
         Block to = event.getToBlock();
         Material fromType = from.getType();

src/main/java/com/sk89q/worldguard/bukkit/listener/RegionProtectionListener.java

@@ -113,6 +113,11 @@ public void onPlaceBlock(final PlaceBlockEvent event) {
         final RegionQuery query = getPlugin().getRegionContainer().createQuery();
         final RegionAssociable associable = createRegionAssociable(event.getCause());
 
+        // Don't check liquid flow unless it's enabled
+        if (Materials.isLiquid(type) && !getWorldConfig(event.getWorld()).checkLiquidFlow) {
+            return;
+        }
+
         event.filter(new Predicate<Location>() {
             @Override
             public boolean apply(Location target) {