diff --git a/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp b/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
index 2c9a4afeb5..a3723253b5 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
@@ -109,8 +109,7 @@ using namespace Gen;
 		links_to.clear();
 		block_map.clear();
 
-		valid_block.clear();
-		valid_block.resize(VALID_BLOCK_MASK_SIZE, false);
+		valid_block.ClearAll();
 
 		num_blocks = 0;
 		memset(blockCodePointers, 0, sizeof(u8*)*MAX_NUM_BLOCKS);
@@ -165,7 +164,7 @@ using namespace Gen;
 		u32 pAddr = b.originalAddress & 0x1FFFFFFF;
 
 		for (u32 i = 0; i < (b.originalSize + 7) / 8; ++i)
-			valid_block[pAddr / 32 + i] = true;
+			valid_block.Set(pAddr / 32 + i);
 
 		block_map[std::make_pair(pAddr + 4 * b.originalSize - 1, pAddr)] = block_num;
 		if (block_link)
@@ -335,10 +334,10 @@ using namespace Gen;
 		bool destroy_block = true;
 		if (length == 32)
 		{
-			if (!valid_block[pAddr / 32])
+			if (!valid_block.Test(pAddr / 32))
 				destroy_block = false;
 			else
-				valid_block[pAddr / 32] = false;
+				valid_block.Clear(pAddr / 32);
 		}
 
 		// destroy JIT blocks
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitCache.h b/Source/Core/Core/PowerPC/JitCommon/JitCache.h
index ada410a420..5f5b6aaa0a 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitCache.h
+++ b/Source/Core/Core/PowerPC/JitCommon/JitCache.h
@@ -6,6 +6,7 @@
 
 #include <bitset>
 #include <map>
+#include <memory>
 #include <vector>
 
 #include "Core/PowerPC/Gekko.h"
@@ -64,6 +65,40 @@ struct JitBlock
 
 typedef void (*CompiledCode)();
 
+// This is essentially just an std::bitset, but Visual Studia 2013's
+// implementation of std::bitset is slow.
+class ValidBlockBitSet final
+{
+	enum
+	{
+		VALID_BLOCK_MASK_SIZE = 0x20000000 / 32,
+		VALID_BLOCK_ALLOC_ELEMENTS = VALID_BLOCK_MASK_SIZE / 32
+	};
+	std::unique_ptr<u32[]> m_valid_block;
+
+public:
+	ValidBlockBitSet()
+	{
+		m_valid_block.reset(new u32[VALID_BLOCK_ALLOC_ELEMENTS]);
+		ClearAll();
+	}
+	void Set(u32 bit)
+	{
+		m_valid_block[bit / 32] |= 1u << (bit % 32);
+	}
+	void Clear(u32 bit)
+	{
+		m_valid_block[bit / 32] &= ~(1u << (bit % 32));
+	}
+	void ClearAll()
+	{
+		memset(m_valid_block.get(), 0, sizeof(u32) * VALID_BLOCK_ALLOC_ELEMENTS);
+	}
+	bool Test(u32 bit)
+	{
+		return (m_valid_block[bit / 32] & (1u << (bit % 32))) != 0;
+	}
+};
 
 class JitBaseBlockCache
 {
@@ -72,11 +107,11 @@ class JitBaseBlockCache
 	int num_blocks;
 	std::multimap<u32, int> links_to;
 	std::map<std::pair<u32,u32>, u32> block_map; // (end_addr, start_addr) -> number
-	std::vector<bool> valid_block;
+	ValidBlockBitSet valid_block;
+
 	enum
 	{
 		MAX_NUM_BLOCKS = 65536*2,
-		VALID_BLOCK_MASK_SIZE = 0x20000000 / 32,
 	};
 
 	bool RangeIntersect(int s1, int e1, int s2, int e2) const;