diff --git a/desmume/src/MMU.cpp b/desmume/src/MMU.cpp
index 3c1c9c396..c0bcf674a 100644
--- a/desmume/src/MMU.cpp
+++ b/desmume/src/MMU.cpp
@@ -52,6 +52,7 @@
 #define ASSERT_UNALIGNED(x)
 #endif
 
+int LagFrameFlag=0;
 
 
 //http://home.utah.edu/~nahaj/factoring/isqrt.c.html
@@ -2863,6 +2864,12 @@ void FASTCALL _MMU_ARM9_write32(u32 adr, u32 val)
 	T1WriteLong(MMU.MMU_MEM[ARMCPU_ARM9][adr>>20], adr&MMU.MMU_MASK[ARMCPU_ARM9][adr>>20], val);
 }
 
+void CheckLag(u32 adr) {
+
+	if (adr == 0x04000130 || 0x04000136)
+		LagFrameFlag=0;
+}
+
 //================================================= MMU ARM9 read 08
 u8 FASTCALL _MMU_ARM9_read08(u32 adr)
 {
@@ -2884,6 +2891,7 @@ u8 FASTCALL _MMU_ARM9_read08(u32 adr)
 	if ((adr>=0x9000000)&&(adr<0x9900000))
 		return (unsigned char)cflash_read(adr);
 #endif
+	CheckLag(adr);
 
 #ifdef _MMU_DEBUG
 		mmu_log_debug_ARM9(adr, "(read08) %0x%X", 
@@ -2918,6 +2926,8 @@ u16 FASTCALL _MMU_ARM9_read16(u32 adr)
 
 	adr &= 0x0FFFFFFF;
 
+	CheckLag(adr);
+
 	if (adr >> 24 == 4)
 	{
 		/* Address is an IO register */
@@ -3001,6 +3011,8 @@ u32 FASTCALL _MMU_ARM9_read32(u32 adr)
 
 	adr &= 0x0FFFFFFF;
 
+	CheckLag(adr);
+
 	// Address is an IO register
 	if((adr >> 24) == 4)
 	{
diff --git a/desmume/src/MMU.h b/desmume/src/MMU.h
index 8ab88fdc1..b18737757 100644
--- a/desmume/src/MMU.h
+++ b/desmume/src/MMU.h
@@ -126,6 +126,7 @@ struct MMU_struct {
 
 extern MMU_struct MMU;
 
+extern int LagFrameFlag;
 
 struct armcpu_memory_iface {
   /** the 32 bit instruction prefetch */
diff --git a/desmume/src/NDSSystem.cpp b/desmume/src/NDSSystem.cpp
index fa910a8a1..29c86ddc0 100644
--- a/desmume/src/NDSSystem.cpp
+++ b/desmume/src/NDSSystem.cpp
@@ -64,6 +64,8 @@ BOOL fw_success = FALSE;
 
 NDSSystem nds;
 
+int lagframecounter=0;
+
 /* ------------------------------------------------------------------------- */
 /* FIRMWARE DECRYPTION */
 
@@ -1420,6 +1422,8 @@ u32 NDS_exec(s32 nb)
 {
 	int i, j;
 
+	LagFrameFlag=1;
+
 	nb += nds.cycles;//(nds.cycles>>26)<<26;
 
 	//increase this to execute more instructions in each batch (reducing overhead)
@@ -2208,6 +2212,9 @@ u32 NDS_exec(s32 nb)
 		}
 	}
 
+	if(LagFrameFlag)
+		lagframecounter++;
+
 	return nds.cycles;
 }
 
diff --git a/desmume/src/NDSSystem.h b/desmume/src/NDSSystem.h
index 4230b3a41..45113a7b0 100644
--- a/desmume/src/NDSSystem.h
+++ b/desmume/src/NDSSystem.h
@@ -235,6 +235,8 @@ void NDS_SkipFrame(bool skip);
 template<bool FORCE>
 u32 NDS_exec(s32 nb);
 
+extern int lagframecounter;
+
 inline u32 NDS_exec(s32 nb) { return NDS_exec<false>(nb); }
 
        static INLINE void NDS_ARM9HBlankInt(void)
diff --git a/desmume/src/windows/main.cpp b/desmume/src/windows/main.cpp
index 4fe15fde5..518e0a600 100644
--- a/desmume/src/windows/main.cpp
+++ b/desmume/src/windows/main.cpp
@@ -225,6 +225,7 @@ bool frameAdvance = false;
 bool frameCounterDisplay = false;
 bool FpsDisplay = false;
 bool ShowInputDisplay = false;
+bool ShowLagFrameCounter = false;
 unsigned short windowSize = 0;
 
 unsigned int lastSaveState = 0;	//Keeps track of last savestate used for quick save/load functions
@@ -1014,6 +1015,7 @@ DWORD WINAPI run()
 				frameCounter++;
 				if (frameCounterDisplay) osd->addFixed(0, 25, "%d",frameCounter);
 				if (ShowInputDisplay) osd->addFixed(0, 45, "%s",InputDisplayString.c_str());
+				if (ShowLagFrameCounter) osd->addFixed(0, 65, "%d",lagframecounter);
 				DisplayMessage();
 				CheckMessages();
 		}
@@ -1072,6 +1074,7 @@ BOOL LoadROM(char * filename, const char *cflash_disk_image)
 	{
 		INFO("Loading %s was successful\n",filename);
 		frameCounter=0;
+		lagframecounter=0;
 		UpdateRecentRoms(filename);
 		osd->setRotate(GPU_rotation);
 		return TRUE;		
@@ -1108,6 +1111,7 @@ int MenuInit()
 
 	MainWindow->checkMenu(ID_VIEW_DISPLAYFPS, FpsDisplay ? MF_CHECKED : MF_UNCHECKED);
 	MainWindow->checkMenu(ID_VIEW_DISPLAYINPUT, ShowInputDisplay ? MF_CHECKED : MF_UNCHECKED);
+	MainWindow->checkMenu(ID_VIEW_DISPLAYLAG, ShowLagFrameCounter ? MF_CHECKED : MF_UNCHECKED);
 
 	MainWindow->checkMenu(IDC_WINDOW1X, MF_BYCOMMAND | ((windowSize==1)?MF_CHECKED:MF_UNCHECKED));
 	MainWindow->checkMenu(IDC_WINDOW1_5X, MF_BYCOMMAND | ((windowSize==65535)?MF_CHECKED:MF_UNCHECKED));
@@ -1344,6 +1348,7 @@ int WINAPI WinMain (HINSTANCE hThisInstance,
 	WndY = GetPrivateProfileInt("Video","WindowPosY", CW_USEDEFAULT, IniName);
 	frameCounterDisplay = GetPrivateProfileInt("Display","FrameCounter", 0, IniName);
 	ShowInputDisplay = GetPrivateProfileInt("Display","Display Input", 0, IniName);
+	ShowLagFrameCounter = GetPrivateProfileInt("Display","Display Lag Counter", 0, IniName);
 	ScreenGap = GetPrivateProfileInt("Display", "ScreenGap", 0, IniName);
 	FrameLimit = GetPrivateProfileInt("FrameLimit", "FrameLimit", 1, IniName);
 	//sprintf(text, "%s", DESMUME_NAME_AND_VERSION);
@@ -2756,6 +2761,13 @@ LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM
 			osd->clear();
 			return 0;
 
+		case ID_VIEW_DISPLAYLAG:
+			ShowLagFrameCounter ^= 1;
+			MainWindow->checkMenu(ID_VIEW_DISPLAYINPUT, ShowLagFrameCounter ? MF_CHECKED : MF_UNCHECKED);
+			WritePrivateProfileInt("Display", "Display Lag Counter", ShowLagFrameCounter, IniName);
+			osd->clear();
+			return 0;
+
 #define clearsaver() \
 	MainWindow->checkMenu(IDC_SAVETYPE1, MF_BYCOMMAND | MF_UNCHECKED); \
 	MainWindow->checkMenu(IDC_SAVETYPE2, MF_BYCOMMAND | MF_UNCHECKED); \
diff --git a/desmume/src/windows/resource.h b/desmume/src/windows/resource.h
index 45c7155b9..2d8a2b3dc 100644
--- a/desmume/src/windows/resource.h
+++ b/desmume/src/windows/resource.h
@@ -416,6 +416,7 @@
 #define ID_VIEW_FRAMECOUNTER                    40009
 #define ID_VIEW_DISPLAYFPS                      40010
 #define ID_VIEW_DISPLAYINPUT                    40011
+#define ID_VIEW_DISPLAYLAG	                    40012
 #define IDM_FILE_RECORDAVI                      40015
 #define IDM_FILE_STOPAVI                        40016
 #define ACCEL_CTRL_O                            40032
diff --git a/desmume/src/windows/resources.rc b/desmume/src/windows/resources.rc
index 900dbabba..ed4d27373 100644
--- a/desmume/src/windows/resources.rc
+++ b/desmume/src/windows/resources.rc
@@ -114,6 +114,7 @@ BEGIN
         MENUITEM "Display Frame Counter", ID_VIEW_FRAMECOUNTER
         MENUITEM "Display Fps", ID_VIEW_DISPLAYFPS
 		MENUITEM "Display Input", ID_VIEW_DISPLAYINPUT
+		MENUITEM "Display Lag Counter", ID_VIEW_DISPLAYLAG
     END
     POPUP "&Konfigure"
     BEGIN
@@ -282,6 +283,7 @@ BEGIN
         MENUITEM "Display Frame Counter", ID_VIEW_FRAMECOUNTER
         MENUITEM "Display FPS", ID_VIEW_DISPLAYFPS
 		MENUITEM "Display Input", ID_VIEW_DISPLAYINPUT
+		MENUITEM "Display Lag Counter", ID_VIEW_DISPLAYLAG
     END
     POPUP "&Config"
     BEGIN
@@ -449,6 +451,7 @@ BEGIN
         MENUITEM "Compteur d'images", ID_VIEW_FRAMECOUNTER
         MENUITEM "Framerate", ID_VIEW_DISPLAYFPS
 		MENUITEM "Display Input", ID_VIEW_DISPLAYINPUT
+		MENUITEM "Display Lag Counter", ID_VIEW_DISPLAYLAG
     END
     POPUP "&Config"
     BEGIN