diff --git a/core/cheats.cpp b/core/cheats.cpp
index 77a20a9e6..45b427d85 100644
--- a/core/cheats.cpp
+++ b/core/cheats.cpp
@@ -481,6 +481,19 @@ void CheatManager::reset(const std::string& gameId)
 			else if (gameId == "MKG TKOB 2 KOR VER1.000-")	// mushik2k
 				setMushikingCheats(0x706084);
 		}
+		else if (gameId == "T-8120N")		// Dave Mirra BMX (US)
+		{
+			setActive(true);
+			cheats.emplace_back(Cheat::Type::setValue, "fix main loop time", true, 32, 0x0030b8cc, 0x42040000); // 33.0 ms
+			cheats.back().builtIn = true;
+		}
+		else if (gameId == "T8120D  50")	// Dave Mirra BMX (EU)
+		{
+			setActive(true);
+			cheats.emplace_back(Cheat::Type::setValue, "fix main loop time", true, 32, 0x003011cc, 0x42200000); // 40.0 ms
+			cheats.back().builtIn = true;
+		}
+
 	}
 	if (config::WidescreenGameHacks)
 	{
diff --git a/core/hw/sh4/sh4_cycles.h b/core/hw/sh4/sh4_cycles.h
index 46354980f..1d517c675 100644
--- a/core/hw/sh4/sh4_cycles.h
+++ b/core/hw/sh4/sh4_cycles.h
@@ -53,16 +53,48 @@ public:
 		sh4_opcodelistentry *opcode = OpDesc[op];
 		int cycles = 0;
 #ifndef STRICT_MODE
-		if (opcode->ex_type == 2 || opcode->ex_type == 3
-				|| opcode->ex_type == 5 || opcode->ex_type == 6 || opcode->ex_type == 7
-				// cache mgmt || opcode->ex_type == 10 || opcode->ex_type == 11
-				|| opcode->ex_type == 12
-				|| opcode->ex_type == 17 || opcode->ex_type == 18 || opcode->ex_type == 19
-				|| opcode->ex_type == 22 || opcode->ex_type == 23 || opcode->ex_type == 25
-				|| opcode->ex_type == 27 || opcode->ex_type == 29 || opcode->ex_type == 31
-				|| opcode->ex_type == 33 || opcode->ex_type == 35)
+		static const bool isMemOp[45] {
+			false,
+			false,
+			true,	// all mem moves, ldtlb, sts.l FPUL/FPSCR, @-Rn, lds.l @Rn+,FPUL
+			true,	// gbr-based load/store
+			false,
+			true,	// tst.b #<imm8>, @(R0,GBR)
+			true,	// and/or/xor.b #<imm8>, @(R0,GBR)
+			true,	// tas.b @Rn
+			false,
+			false,
+			false,
+			false,
+			true,	// movca.l R0, @Rn
+			false,
+			false,
+			false,
+			false,
+			true,	// ldc.l @Rn+, VBR/SPC/SSR/Rn_Bank/DBR
+			true,	// ldc.l @Rn+, GBR/SGR
+			true,	// ldc.l @Rn+, SR
+			false,
+			false,
+			true,	// stc.l DBR/SR/GBR/VBR/SSR/SPC/Rn_Bank, @-Rn
+			true,	// stc.l SGR, @-Rn
+			false,
+			true,	// lds.l @Rn+, PR
+			false,
+			true,	// sts.l PR, @-Rn
+			false,
+			true,	// lds.l @Rn+, MACH/MACL
+			false,
+			true,	// sts.l MACH/MACL, @-Rn
+			false,
+			true,	// lds.l @Rn+,FPSCR
+			false,
+			true,	// mac.wl @Rm+,@Rn+
+		};
+		if (isMemOp[opcode->ex_type])
 		{
-			cycles = mmu_enabled() ? 5 : 2;
+			if (++memOps < 4)
+				cycles = mmu_enabled() ? 5 : 2;
 		}
 		// TODO only for mem read?
 #endif
@@ -86,6 +118,7 @@ public:
 	void reset()
 	{
 		lastUnit = CO;
+		memOps = 0;
 	}
 
 	static u64 now() {
@@ -108,6 +141,7 @@ private:
 
 	sh4_eu lastUnit = CO;
 	const int cpuRatio;
+	int memOps = 0;
 };
 
 extern Sh4Cycles sh4cycles;