diff --git a/src/BlockEntities/BlockEntityWithItems.cpp b/src/BlockEntities/BlockEntityWithItems.cpp
index 1a8ae4342..b2f225aa7 100644
--- a/src/BlockEntities/BlockEntityWithItems.cpp
+++ b/src/BlockEntities/BlockEntityWithItems.cpp
@@ -58,10 +58,10 @@ void cBlockEntityWithItems::OnSlotChanged(cItemGrid * a_Grid, int a_SlotNum)
 		auto & Simulator = *m_World->GetRedstoneSimulator();
 
 		// Notify comparators:
-		Simulator.WakeUp(m_Pos + Vector3i(1, 0, 0), &a_Chunk);
-		Simulator.WakeUp(m_Pos + Vector3i(-1, 0, 0), &a_Chunk);
-		Simulator.WakeUp(m_Pos + Vector3i(0, 0, 1), &a_Chunk);
-		Simulator.WakeUp(m_Pos + Vector3i(0, 0, -1), &a_Chunk);
+		m_World->WakeUpSimulators(m_Pos + Vector3i(1, 0, 0));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(-1, 0, 0));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(0, 0, 1));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(0, 0, -1));
 		return true;
 	});
 }
diff --git a/src/BlockEntities/ChestEntity.cpp b/src/BlockEntities/ChestEntity.cpp
index d9648df18..cb26f4d08 100644
--- a/src/BlockEntities/ChestEntity.cpp
+++ b/src/BlockEntities/ChestEntity.cpp
@@ -216,3 +216,42 @@ bool cChestEntity::IsBlocked()
 
 
 
+
+void cChestEntity::OnSlotChanged(cItemGrid * a_Grid, int a_SlotNum)
+{
+	ASSERT(a_Grid == &m_Contents);
+
+	if (m_World == nullptr)
+	{
+		return;
+	}
+
+	// Have cBlockEntityWithItems update redstone and try to broadcast our window:
+	Super::OnSlotChanged(a_Grid, a_SlotNum);
+
+	cWindow * Window = GetWindow();
+	if ((Window == nullptr) && (m_Neighbour != nullptr))
+	{
+		// Window was null, Super will have failed.
+		// Neighbour might own the window:
+		Window = m_Neighbour->GetWindow();
+	}
+
+	if (Window != nullptr)
+	{
+		Window->BroadcastWholeWindow();
+	}
+
+	m_World->MarkChunkDirty(GetChunkX(), GetChunkZ());
+	m_World->DoWithChunkAt(m_Pos, [&](cChunk & a_Chunk)
+	{
+		auto & Simulator = *m_World->GetRedstoneSimulator();
+
+		// Notify comparators:
+		m_World->WakeUpSimulators(m_Pos + Vector3i(1, 0, 0));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(-1, 0, 0));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(0, 0, 1));
+		m_World->WakeUpSimulators(m_Pos + Vector3i(0, 0, -1));
+		return true;
+	});
+}
diff --git a/src/BlockEntities/ChestEntity.h b/src/BlockEntities/ChestEntity.h
index c6d13fa38..84b6eef0c 100644
--- a/src/BlockEntities/ChestEntity.h
+++ b/src/BlockEntities/ChestEntity.h
@@ -74,44 +74,7 @@ private:
 	cChestEntity * m_Neighbour;
 
 	/** cItemGrid::cListener overrides: */
-	virtual void OnSlotChanged(cItemGrid * a_Grid, int a_SlotNum) override
-	{
-		ASSERT(a_Grid == &m_Contents);
-
-		if (m_World == nullptr)
-		{
-			return;
-		}
-
-		// Have cBlockEntityWithItems update redstone and try to broadcast our window:
-		Super::OnSlotChanged(a_Grid, a_SlotNum);
-
-		cWindow * Window = GetWindow();
-		if ((Window == nullptr) && (m_Neighbour != nullptr))
-		{
-			// Window was null, Super will have failed.
-			// Neighbour might own the window:
-			Window = m_Neighbour->GetWindow();
-		}
-
-		if (Window != nullptr)
-		{
-			Window->BroadcastWholeWindow();
-		}
-
-		m_World->MarkChunkDirty(GetChunkX(), GetChunkZ());
-		m_World->DoWithChunkAt(m_Pos, [&](cChunk & a_Chunk)
-		{
-			auto & Simulator = *m_World->GetRedstoneSimulator();
-
-			// Notify comparators:
-			Simulator.WakeUp(m_Pos + Vector3i(1, 0, 0), &a_Chunk);
-			Simulator.WakeUp(m_Pos + Vector3i(-1, 0, 0), &a_Chunk);
-			Simulator.WakeUp(m_Pos + Vector3i(0, 0, 1), &a_Chunk);
-			Simulator.WakeUp(m_Pos + Vector3i(0, 0, -1), &a_Chunk);
-			return true;
-		});
-	}
+	virtual void OnSlotChanged(cItemGrid * a_Grid, int a_SlotNum) override;
 
 } ;  // tolua_export
 
diff --git a/src/Blocks/BlockVine.h b/src/Blocks/BlockVine.h
index 2cf6e985c..68e6e2ddc 100644
--- a/src/Blocks/BlockVine.h
+++ b/src/Blocks/BlockVine.h
@@ -196,8 +196,7 @@ public:
 		}
 		else
 		{
-			auto absPos = a_Chunk.RelativeToAbsolute(a_RelPos);
-			a_Chunk.GetWorld()->GetSimulatorManager()->WakeUp(absPos, &a_Chunk);
+			a_Chunk.GetWorld()->GetSimulatorManager()->WakeUp(a_Chunk, a_RelPos);
 		}
 	}
 
diff --git a/src/Chunk.cpp b/src/Chunk.cpp
index cb14b36a0..1c06ed3b3 100644
--- a/src/Chunk.cpp
+++ b/src/Chunk.cpp
@@ -1241,40 +1241,12 @@ void cChunk::WakeUpSimulators(void)
 
 		for (size_t BlockIdx = 0; BlockIdx != cChunkData::SectionBlockCount; ++BlockIdx)
 		{
-			auto BlockType = Section->m_BlockTypes[BlockIdx];
+			const auto BlockType = Section->m_BlockTypes[BlockIdx];
+			const auto Position = IndexToCoordinate(BlockIdx);
 
-			// Defer calculation until it's actually needed
-			auto WorldPos = [&]
-			{
-				auto RelPos = IndexToCoordinate(BlockIdx);
-				RelPos.y += static_cast<int>(SectionIdx * cChunkData::SectionHeight);
-				return RelativeToAbsolute(RelPos);
-			};
-
-			// The redstone sim takes multiple blocks, use the inbuilt checker
-			if (RedstoneSimulator->IsAllowedBlock(BlockType))
-			{
-				RedstoneSimulator->AddBlock(WorldPos(), this);
-				continue;
-			}
-
-			switch (BlockType)
-			{
-				case E_BLOCK_WATER:
-				{
-					WaterSimulator->AddBlock(WorldPos(), this);
-					break;
-				}
-				case E_BLOCK_LAVA:
-				{
-					LavaSimulator->AddBlock(WorldPos(), this);
-					break;
-				}
-				default:
-				{
-					break;
-				}
-			}  // switch (BlockType)
+			RedstoneSimulator->AddBlock(*this, Position, BlockType);
+			WaterSimulator->AddBlock(*this, Position, BlockType);
+			LavaSimulator->AddBlock(*this, Position, BlockType);
 		}
 	}
 }
@@ -1316,7 +1288,7 @@ void cChunk::SetBlock(Vector3i a_RelPos, BLOCKTYPE a_BlockType, NIBBLETYPE a_Blo
 
 	// TODO: use relative coordinates, cChunk reference
 	// Wake up the simulators for this block:
-	GetWorld()->GetSimulatorManager()->WakeUp(RelativeToAbsolute(a_RelPos), this);
+	GetWorld()->GetSimulatorManager()->WakeUp(*this, a_RelPos);
 
 	// If there was a block entity, remove it:
 	cBlockEntity * BlockEntity = GetBlockEntityRel(a_RelPos);
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index 43253a91d..6b1ece612 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -227,7 +227,8 @@ void cChunkMap::WakeUpSimulators(Vector3i a_Block)
 	{
 		return;
 	}
-	m_World->GetSimulatorManager()->WakeUp(a_Block, Chunk);
+
+	m_World->GetSimulatorManager()->WakeUp(*Chunk, cChunkDef::AbsoluteToRelative(a_Block, Chunk->GetPos()));
 }
 
 
@@ -644,7 +645,6 @@ void cChunkMap::SetBlock(Vector3i a_BlockPos, BLOCKTYPE a_BlockType, NIBBLETYPE
 		BlockHandler(blockType)->OnBroken(ChunkInterface, *m_World, a_BlockPos, blockType, blockMeta);
 
 		chunk->SetBlock(relPos, a_BlockType, a_BlockMeta);
-		m_World->GetSimulatorManager()->WakeUp(a_BlockPos, chunk);
 		BlockHandler(a_BlockType)->OnPlaced(ChunkInterface, *m_World, a_BlockPos, a_BlockType, a_BlockMeta);
 	}
 }
@@ -867,7 +867,6 @@ bool cChunkMap::DigBlock(Vector3i a_BlockPos)
 		}
 
 		destChunk->SetBlock(relPos, E_BLOCK_AIR, 0);
-		m_World->GetSimulatorManager()->WakeUp(a_BlockPos, destChunk);
 	}
 	return true;
 }
diff --git a/src/Simulator/DelayedFluidSimulator.cpp b/src/Simulator/DelayedFluidSimulator.cpp
index af9007548..b27e34e5f 100644
--- a/src/Simulator/DelayedFluidSimulator.cpp
+++ b/src/Simulator/DelayedFluidSimulator.cpp
@@ -78,27 +78,15 @@ cDelayedFluidSimulator::cDelayedFluidSimulator(cWorld & a_World, BLOCKTYPE a_Flu
 
 
 
-void cDelayedFluidSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
+void cDelayedFluidSimulator::WakeUp(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	int RelX = a_Block.x - a_Chunk->GetPosX() * cChunkDef::Width;
-	int RelZ = a_Block.z - a_Chunk->GetPosZ() * cChunkDef::Width;
-	BLOCKTYPE BlockType = a_Chunk->GetBlock(RelX, a_Block.y, RelZ);
-	if (BlockType != m_FluidBlock)
+	if (!cChunkDef::IsValidHeight(a_Position.y))
 	{
+		// Not inside the world (may happen when rclk with a full bucket - the client sends Y = -1)
 		return;
 	}
 
-	auto ChunkDataRaw = (m_FluidBlock == E_BLOCK_WATER) ? a_Chunk->GetWaterSimulatorData() : a_Chunk->GetLavaSimulatorData();
-	cDelayedFluidSimulatorChunkData * ChunkData = static_cast<cDelayedFluidSimulatorChunkData *>(ChunkDataRaw);
-	cDelayedFluidSimulatorChunkData::cSlot & Slot = ChunkData->m_Slots[m_AddSlotNum];
-
-	// Add, if not already present:
-	if (!Slot.Add(RelX, a_Block.y, RelZ))
-	{
-		return;
-	}
-
-	++m_TotalBlocks;
+	Super::WakeUp(a_Chunk, a_Position, a_Block);
 }
 
 
@@ -146,13 +134,22 @@ void cDelayedFluidSimulator::SimulateChunk(std::chrono::milliseconds a_Dt, int a
 
 
 
-void cDelayedFluidSimulator::WakeUp(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
+void cDelayedFluidSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	if (!cChunkDef::IsValidHeight(a_Position.y))
+	if (a_Block != m_FluidBlock)
 	{
-		// Not inside the world (may happen when rclk with a full bucket - the client sends Y = -1)
 		return;
 	}
 
-	Super::WakeUp(a_Chunk, a_Position, a_Block);
+	auto ChunkDataRaw = (m_FluidBlock == E_BLOCK_WATER) ? a_Chunk.GetWaterSimulatorData() : a_Chunk.GetLavaSimulatorData();
+	cDelayedFluidSimulatorChunkData * ChunkData = static_cast<cDelayedFluidSimulatorChunkData *>(ChunkDataRaw);
+	cDelayedFluidSimulatorChunkData::cSlot & Slot = ChunkData->m_Slots[m_AddSlotNum];
+
+	// Add, if not already present:
+	if (!Slot.Add(a_Position.x, a_Position.y, a_Position.z))
+	{
+		return;
+	}
+
+	++m_TotalBlocks;
 }
diff --git a/src/Simulator/DelayedFluidSimulator.h b/src/Simulator/DelayedFluidSimulator.h
index b3158efec..e307e4ad7 100644
--- a/src/Simulator/DelayedFluidSimulator.h
+++ b/src/Simulator/DelayedFluidSimulator.h
@@ -54,15 +54,15 @@ public:
 
 	cDelayedFluidSimulator(cWorld & a_World, BLOCKTYPE a_Fluid, BLOCKTYPE a_StationaryFluid, int a_TickDelay);
 
-	// cSimulator overrides:
 	virtual void WakeUp(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
-	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
-	virtual void Simulate(float a_Dt) override;
-	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
-	virtual cFluidSimulatorData * CreateChunkData(void) override { return new cDelayedFluidSimulatorChunkData(m_TickDelay); }
 
 protected:
 
+	virtual void Simulate(float a_Dt) override;
+	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
+	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
+	virtual cFluidSimulatorData * CreateChunkData(void) override { return new cDelayedFluidSimulatorChunkData(m_TickDelay); }
+
 	int m_TickDelay;   // Count of the m_Slots array in each ChunkData
 	int m_AddSlotNum;  // Index into m_Slots[] where to add new blocks in each ChunkData
 	int m_SimSlotNum;  // Index into m_Slots[] where to simulate blocks in each ChunkData
diff --git a/src/Simulator/FireSimulator.cpp b/src/Simulator/FireSimulator.cpp
index 1f212e2a5..30fe88acd 100644
--- a/src/Simulator/FireSimulator.cpp
+++ b/src/Simulator/FireSimulator.cpp
@@ -79,14 +79,6 @@ cFireSimulator::cFireSimulator(cWorld & a_World, cIniFile & a_IniFile) :
 
 
 
-cFireSimulator::~cFireSimulator()
-{
-}
-
-
-
-
-
 void cFireSimulator::SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk)
 {
 	cCoordWithIntList & Data = a_Chunk->GetFireSimulatorData();
@@ -241,28 +233,21 @@ bool cFireSimulator::DoesBurnForever(BLOCKTYPE a_BlockType)
 
 void cFireSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	if ((a_Chunk == nullptr) || !a_Chunk->IsValid())
-	{
-		return;
-	}
-
-	const auto RelPos = cChunkDef::AbsoluteToRelative(a_Block, a_Chunk->GetPos());
-	BLOCKTYPE BlockType = a_Chunk->GetBlock(RelPos);
-	if (!IsAllowedBlock(BlockType))
+	if (!IsAllowedBlock(a_Block))
 	{
 		return;
 	}
 
 	// Check for duplicates:
-	cFireSimulatorChunkData & ChunkData = a_Chunk->GetFireSimulatorData();
+	cFireSimulatorChunkData & ChunkData = a_Chunk.GetFireSimulatorData();
 	for (cCoordWithIntList::iterator itr = ChunkData.begin(), end = ChunkData.end(); itr != end; ++itr)
 	{
 		const Vector3i ItrPos{itr->x, itr->y, itr->z};
-		if (ItrPos == RelPos)
+		if (ItrPos == a_Position)
 		{
 			// Block already present, check if burn step should decrease
 			// This means if fuel is removed, then the fire burns out sooner
-			const auto NewBurnStep = GetBurnStepTime(a_Chunk, RelPos);
+			const auto NewBurnStep = GetBurnStepTime(&a_Chunk, a_Position);
 			if (itr->Data > NewBurnStep)
 			{
 				FIRE_FLOG("FS: Block lost its fuel at {0}", a_Block);
@@ -274,7 +259,7 @@ void cFireSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a
 	}  // for itr - ChunkData[]
 
 	FIRE_FLOG("FS: Adding block {0}", a_Block);
-	ChunkData.push_back(cCoordWithInt(RelPos.x, RelPos.y, RelPos.z, 100));
+	ChunkData.push_back(cCoordWithInt(a_Position.x, a_Position.y, a_Position.z, 100));
 }
 
 
diff --git a/src/Simulator/FireSimulator.h b/src/Simulator/FireSimulator.h
index 1bc6e7c0b..1e9b0b6d7 100644
--- a/src/Simulator/FireSimulator.h
+++ b/src/Simulator/FireSimulator.h
@@ -19,18 +19,19 @@ class cFireSimulator :
 	public cSimulator
 {
 public:
+
 	cFireSimulator(cWorld & a_World, cIniFile & a_IniFile);
-	virtual ~cFireSimulator() override;
-
-	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}  // not used
-	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
-
-	virtual bool IsAllowedBlock(BLOCKTYPE a_BlockType) override;
 
 	static bool IsFuel   (BLOCKTYPE a_BlockType);
 	static bool DoesBurnForever(BLOCKTYPE a_BlockType);
 
-protected:
+private:
+
+	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}  // not used
+	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
+
+	static bool IsAllowedBlock(BLOCKTYPE a_BlockType);
+
 	/** Time (in msec) that a fire block takes to burn with a fuel block into the next step */
 	unsigned m_BurnStepTimeFuel;
 
diff --git a/src/Simulator/FloodyFluidSimulator.cpp b/src/Simulator/FloodyFluidSimulator.cpp
index c63d7e965..5f4d5ba85 100644
--- a/src/Simulator/FloodyFluidSimulator.cpp
+++ b/src/Simulator/FloodyFluidSimulator.cpp
@@ -309,7 +309,7 @@ void cFloodyFluidSimulator::SpreadToNeighbor(cChunk * a_NearChunk, int a_RelX, i
 	// Spread:
 	FLUID_FLOG("  Spreading to {0} with meta {1}", absPos, a_NewMeta);
 	a_NearChunk->SetBlock(relPos, m_FluidBlock, a_NewMeta);
-	m_World.GetSimulatorManager()->WakeUp(absPos, a_NearChunk);
+	m_World.GetSimulatorManager()->WakeUp(*a_NearChunk, relPos);
 
 	HardenBlock(a_NearChunk, relPos, m_FluidBlock, a_NewMeta);
 }
diff --git a/src/Simulator/FluidSimulator.h b/src/Simulator/FluidSimulator.h
index e9157fa69..2dc499375 100644
--- a/src/Simulator/FluidSimulator.h
+++ b/src/Simulator/FluidSimulator.h
@@ -43,14 +43,11 @@ public:
 
 	cFluidSimulator(cWorld & a_World, BLOCKTYPE a_Fluid, BLOCKTYPE a_StationaryFluid);
 
-	// cSimulator overrides:
-	virtual bool IsAllowedBlock(BLOCKTYPE a_BlockType) override;
-
 	/** Returns a unit vector in the direction the fluid is flowing or a zero-vector if not flowing. */
 	virtual Vector3f GetFlowingDirection(int a_X, int a_Y, int a_Z);
 
 	/** Creates a ChunkData object for the simulator to use. The simulator returns the correct object type. */
-	virtual cFluidSimulatorData * CreateChunkData(void) { return nullptr; }
+	virtual cFluidSimulatorData * CreateChunkData(void) = 0;
 
 	bool IsFluidBlock          (BLOCKTYPE a_BlockType) const { return (a_BlockType == m_FluidBlock); }
 	bool IsStationaryFluidBlock(BLOCKTYPE a_BlockType) const { return (a_BlockType == m_StationaryFluidBlock); }
@@ -65,6 +62,9 @@ public:
 	bool IsHigherMeta(NIBBLETYPE a_Meta1, NIBBLETYPE a_Meta2);
 
 protected:
+
+	bool IsAllowedBlock(BLOCKTYPE a_BlockType);
+
 	BLOCKTYPE m_FluidBlock;            // The fluid block type that needs simulating
 	BLOCKTYPE m_StationaryFluidBlock;  // The fluid block type that indicates no simulation is needed
 };
diff --git a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
index 33c0f9523..f2c8b7e65 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
+++ b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.cpp
@@ -273,26 +273,18 @@ void cIncrementalRedstoneSimulator::ProcessWorkItem(cChunk & Chunk, cChunk & Tic
 
 void cIncrementalRedstoneSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	// Can't inspect block, ignore:
-	if ((a_Chunk == nullptr) || !a_Chunk->IsValid())
+	auto & ChunkData = *static_cast<cIncrementalRedstoneSimulatorChunkData *>(a_Chunk.GetRedstoneSimulatorData());
+
+	if (!IsRedstone(a_Block))
 	{
 		return;
 	}
 
-	auto & ChunkData = *static_cast<cIncrementalRedstoneSimulatorChunkData *>(a_Chunk->GetRedstoneSimulatorData());
-	const auto Relative = cChunkDef::AbsoluteToRelative(a_Block, a_Chunk->GetPos());
-	const auto CurrentBlock = a_Chunk->GetBlock(Relative);
-
-	if (!IsRedstone(CurrentBlock))
+	if (IsAlwaysTicked(a_Block))
 	{
-		return;
-	}
-
-	if (IsAlwaysTicked(CurrentBlock))
-	{
-		ChunkData.AlwaysTickedPositions.emplace(Relative);
+		ChunkData.AlwaysTickedPositions.emplace(a_Position);
 	}
 
 	// Always update redstone devices:
-	ChunkData.WakeUp(Relative);
+	ChunkData.WakeUp(a_Position);
 }
diff --git a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.h b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.h
index 7f1a6a9cf..44c63a5a8 100644
--- a/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.h
+++ b/src/Simulator/IncrementalRedstoneSimulator/IncrementalRedstoneSimulator.h
@@ -21,26 +21,7 @@ public:
 	{
 	}
 
-private:
-
-	virtual void WakeUp(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
-
-	virtual void Simulate(float Dt) override {};
-	virtual void SimulateChunk(std::chrono::milliseconds Dt, int ChunkX, int ChunkZ, cChunk * Chunk) override;
-
-	void ProcessWorkItem(cChunk & Chunk, cChunk & TickingSource, const Vector3i Position);
-
-	virtual cIncrementalRedstoneSimulatorChunkData * CreateChunkData() override
-	{
-		return new cIncrementalRedstoneSimulatorChunkData;
-	}
-
-	virtual bool IsAllowedBlock(BLOCKTYPE a_BlockType) override
-	{
-		return IsRedstone(a_BlockType);
-	}
-
-	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
+	static const cRedstoneHandler * GetComponentHandler(BLOCKTYPE a_BlockType);
 
 	/** Returns if a block is a mechanism (something that accepts power and does something)
 	Used by torches to determine if they will power a block */
@@ -164,7 +145,20 @@ private:
 		}
 	}
 
-	static const cRedstoneHandler * GetComponentHandler(BLOCKTYPE a_BlockType);
+private:
+
+	virtual void WakeUp(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
+	virtual void Simulate(float Dt) override {};
+	virtual void SimulateChunk(std::chrono::milliseconds Dt, int ChunkX, int ChunkZ, cChunk * Chunk) override;
+
+	void ProcessWorkItem(cChunk & Chunk, cChunk & TickingSource, const Vector3i Position);
+
+	virtual cIncrementalRedstoneSimulatorChunkData * CreateChunkData() override
+	{
+		return new cIncrementalRedstoneSimulatorChunkData;
+	}
+
+	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
 
 private:
 
diff --git a/src/Simulator/NoopFluidSimulator.h b/src/Simulator/NoopFluidSimulator.h
index 71c37d92d..2be4f86a9 100644
--- a/src/Simulator/NoopFluidSimulator.h
+++ b/src/Simulator/NoopFluidSimulator.h
@@ -22,18 +22,17 @@ class cNoopFluidSimulator:
 
 public:
 
-	cNoopFluidSimulator(cWorld & a_World, BLOCKTYPE a_Fluid, BLOCKTYPE a_StationaryFluid):
-		Super(a_World, a_Fluid, a_StationaryFluid)
-	{
-	}
+	using Super::cFluidSimulator;
 
-	// cSimulator overrides:
+private:
+
+	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}
 	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override
 	{
 		UNUSED(a_Block);
 		UNUSED(a_Chunk);
 	}
-	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}
+	virtual cFluidSimulatorData * CreateChunkData(void) override { return nullptr; }
 } ;
 
 
diff --git a/src/Simulator/NoopRedstoneSimulator.h b/src/Simulator/NoopRedstoneSimulator.h
index 8d47ceccf..746ee1886 100644
--- a/src/Simulator/NoopRedstoneSimulator.h
+++ b/src/Simulator/NoopRedstoneSimulator.h
@@ -20,14 +20,6 @@ public:
 	}
 
 	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}  // not used
-	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override
-	{
-		UNUSED(a_Dt);
-		UNUSED(a_ChunkX);
-		UNUSED(a_ChunkZ);
-		UNUSED(a_Chunk);
-	}
-	virtual bool IsAllowedBlock( BLOCKTYPE a_BlockType) override { return false; }
 	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override
 	{
 		UNUSED(a_Block);
diff --git a/src/Simulator/SandSimulator.cpp b/src/Simulator/SandSimulator.cpp
index ef02339bc..95f514cc9 100644
--- a/src/Simulator/SandSimulator.cpp
+++ b/src/Simulator/SandSimulator.cpp
@@ -99,29 +99,23 @@ bool cSandSimulator::IsAllowedBlock(BLOCKTYPE a_BlockType)
 
 void cSandSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	if ((a_Chunk == nullptr) || !a_Chunk->IsValid())
-	{
-		return;
-	}
-	int RelX = a_Block.x - a_Chunk->GetPosX() * cChunkDef::Width;
-	int RelZ = a_Block.z - a_Chunk->GetPosZ() * cChunkDef::Width;
-	if (!IsAllowedBlock(a_Chunk->GetBlock(RelX, a_Block.y, RelZ)))
+	if (!IsAllowedBlock(a_Block))
 	{
 		return;
 	}
 
 	// Check for duplicates:
-	cSandSimulatorChunkData & ChunkData = a_Chunk->GetSandSimulatorData();
+	cSandSimulatorChunkData & ChunkData = a_Chunk.GetSandSimulatorData();
 	for (cSandSimulatorChunkData::iterator itr = ChunkData.begin(); itr != ChunkData.end(); ++itr)
 	{
-		if ((itr->x == RelX) && (itr->y == a_Block.y) && (itr->z == RelZ))
+		if ((itr->x == a_Position.x) && (itr->y == a_Position.y) && (itr->z == a_Position.z))
 		{
 			return;
 		}
 	}
 
 	m_TotalBlocks += 1;
-	ChunkData.push_back(cCoordWithInt(RelX, a_Block.y, RelZ));
+	ChunkData.push_back(cCoordWithInt(a_Position.x, a_Position.y, a_Position.z));
 }
 
 
diff --git a/src/Simulator/SandSimulator.h b/src/Simulator/SandSimulator.h
index 665208fbe..113484158 100644
--- a/src/Simulator/SandSimulator.h
+++ b/src/Simulator/SandSimulator.h
@@ -30,11 +30,6 @@ public:
 
 	cSandSimulator(cWorld & a_World, cIniFile & a_IniFile);
 
-	// cSimulator overrides:
-	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}  // not used
-	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
-	virtual bool IsAllowedBlock(BLOCKTYPE a_BlockType) override;
-
 	/** Returns true if a falling-able block can start falling through the specified block type */
 	static bool CanStartFallingThrough(BLOCKTYPE a_BlockType);
 
@@ -56,7 +51,12 @@ public:
 		BLOCKTYPE a_FallingBlockType, NIBBLETYPE a_FallingBlockMeta
 	);
 
-protected:
+private:
+
+	virtual void Simulate(float a_Dt) override { UNUSED(a_Dt);}  // not used
+	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk) override;
+
+	static bool IsAllowedBlock(BLOCKTYPE a_BlockType);
 
 	bool m_IsInstantFall;  // If set to true, blocks don't fall using cFallingBlock entity, but instantly instead
 
diff --git a/src/Simulator/Simulator.h b/src/Simulator/Simulator.h
index 5bd5d8f30..aacd5f52f 100644
--- a/src/Simulator/Simulator.h
+++ b/src/Simulator/Simulator.h
@@ -32,6 +32,7 @@ public:
 protected:
 
 	friend class cChunk;  // Calls AddBlock() in its WakeUpSimulators() function, to speed things up
+	friend class cSimulatorManager;  // Class reponsible for dispatching calls to the various slave Simulators
 
 	virtual void Simulate(float a_Dt) = 0;
 	virtual void SimulateChunk(std::chrono::milliseconds a_Dt, int a_ChunkX, int a_ChunkZ, cChunk * a_Chunk)
@@ -42,11 +43,8 @@ protected:
 		UNUSED(a_Chunk);
 	}
 
-	/** Returns true if the specified block type is "interesting" for this simulator. */
-	virtual bool IsAllowedBlock(BLOCKTYPE a_BlockType) = 0;
-
 	/** Called to simulate a new block. Unlike WakeUp this function will perform minimal checking.
-	It queues the block to be simulated as fast as possible, only making sure that the block type IsAllowedBlock. */
+	It queues the block to be simulated as fast as possible, suitable for area wakeups. */
 	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) = 0;
 
 	/** Called to simulate a single new block, typically as a result of a single block break or change.
diff --git a/src/Simulator/VaporizeFluidSimulator.cpp b/src/Simulator/VaporizeFluidSimulator.cpp
index 8063a0706..82f71c03f 100644
--- a/src/Simulator/VaporizeFluidSimulator.cpp
+++ b/src/Simulator/VaporizeFluidSimulator.cpp
@@ -13,32 +13,14 @@
 
 
 
-cVaporizeFluidSimulator::cVaporizeFluidSimulator(cWorld & a_World, BLOCKTYPE a_Fluid, BLOCKTYPE a_StationaryFluid) :
-	Super(a_World, a_Fluid, a_StationaryFluid)
-{
-}
-
-
-
-
-
 void cVaporizeFluidSimulator::AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block)
 {
-	if (a_Chunk == nullptr)
+	if ((a_Block == m_FluidBlock) || (a_Block == m_StationaryFluidBlock))
 	{
-		return;
-	}
-	auto relPos = cChunkDef::AbsoluteToRelative(a_Block);
-	auto blockType = a_Chunk->GetBlock(relPos);
-	if (
-		(blockType == m_FluidBlock) ||
-		(blockType == m_StationaryFluidBlock)
-	)
-	{
-		a_Chunk->SetBlock(relPos, E_BLOCK_AIR, 0);
+		a_Chunk.FastSetBlock(a_Position, E_BLOCK_AIR, 0);
 		World::GetBroadcastInterface(m_World).BroadcastSoundEffect(
 			"block.fire.extinguish",
-			Vector3d(a_Block),
+			Vector3d(a_Position),
 			1.0f,
 			0.6f
 		);
diff --git a/src/Simulator/VaporizeFluidSimulator.h b/src/Simulator/VaporizeFluidSimulator.h
index 2d259e56e..ef61c9a84 100644
--- a/src/Simulator/VaporizeFluidSimulator.h
+++ b/src/Simulator/VaporizeFluidSimulator.h
@@ -23,11 +23,13 @@ class cVaporizeFluidSimulator:
 
 public:
 
-	cVaporizeFluidSimulator(cWorld & a_World, BLOCKTYPE a_Fluid, BLOCKTYPE a_StationaryFluid);
+	using Super::cFluidSimulator;
+
+private:
 
-	// cSimulator overrides:
-	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
 	virtual void Simulate(float a_Dt) override;
+	virtual void AddBlock(cChunk & a_Chunk, Vector3i a_Position, BLOCKTYPE a_Block) override;
+	virtual cFluidSimulatorData * CreateChunkData(void) override { return nullptr; }
 } ;