diff --git a/Source/Core/Core/PowerPC/BreakPoints.cpp b/Source/Core/Core/PowerPC/BreakPoints.cpp
index 4ef86f95a7..8714efda87 100644
--- a/Source/Core/Core/PowerPC/BreakPoints.cpp
+++ b/Source/Core/Core/PowerPC/BreakPoints.cpp
@@ -11,8 +11,10 @@
 
 #include "Common/CommonTypes.h"
 #include "Common/DebugInterface.h"
+#include "Core/Core.h"
 #include "Core/PowerPC/JitCommon/JitBase.h"
 #include "Core/PowerPC/JitCommon/JitCache.h"
+#include "Core/PowerPC/PowerPC.h"
 
 bool BreakPoints::IsAddressBreakPoint(u32 address) const
 {
@@ -168,13 +170,18 @@ void MemChecks::AddFromStrings(const TMemChecksStr& mc_strings)
 
 void MemChecks::Add(const TMemCheck& memory_check)
 {
-  bool had_any = HasAny();
   if (GetMemCheck(memory_check.start_address) == nullptr)
+  {
+    bool had_any = HasAny();
+    bool lock = Core::PauseAndLock(true);
     m_mem_checks.push_back(memory_check);
-  // If this is the first one, clear the JIT cache so it can switch to
-  // watchpoint-compatible code.
-  if (!had_any && g_jit)
-    g_jit->GetBlockCache()->SchedulateClearCacheThreadSafe();
+    // If this is the first one, clear the JIT cache so it can switch to
+    // watchpoint-compatible code.
+    if (!had_any && g_jit)
+      g_jit->ClearCache();
+    PowerPC::DBATUpdated();
+    Core::PauseAndLock(false, lock);
+  }
 }
 
 void MemChecks::Remove(u32 address)
@@ -183,9 +190,12 @@ void MemChecks::Remove(u32 address)
   {
     if (i->start_address == address)
     {
+      bool lock = Core::PauseAndLock(true);
       m_mem_checks.erase(i);
       if (!HasAny() && g_jit)
-        g_jit->GetBlockCache()->SchedulateClearCacheThreadSafe();
+        g_jit->ClearCache();
+      PowerPC::DBATUpdated();
+      Core::PauseAndLock(false, lock);
       return;
     }
   }
@@ -210,6 +220,25 @@ TMemCheck* MemChecks::GetMemCheck(u32 address)
   return nullptr;
 }
 
+bool MemChecks::OverlapsMemcheck(u32 address, u32 length)
+{
+  if (!HasAny())
+    return false;
+  u32 page_end_suffix = length - 1;
+  u32 page_end_address = address | page_end_suffix;
+  for (TMemCheck memcheck : m_mem_checks)
+  {
+    if (((memcheck.start_address | page_end_suffix) == page_end_address ||
+         (memcheck.end_address | page_end_suffix) == page_end_address) ||
+        ((memcheck.start_address | page_end_suffix) < page_end_address &&
+         (memcheck.end_address | page_end_suffix) > page_end_address))
+    {
+      return true;
+    }
+  }
+  return false;
+}
+
 bool TMemCheck::Action(DebugInterface* debug_interface, u32 value, u32 addr, bool write, int size,
                        u32 pc)
 {
diff --git a/Source/Core/Core/PowerPC/BreakPoints.h b/Source/Core/Core/PowerPC/BreakPoints.h
index b9481b5d18..cce1756513 100644
--- a/Source/Core/Core/PowerPC/BreakPoints.h
+++ b/Source/Core/Core/PowerPC/BreakPoints.h
@@ -87,6 +87,7 @@ public:
 
   // memory breakpoint
   TMemCheck* GetMemCheck(u32 address);
+  bool OverlapsMemcheck(u32 address, u32 length);
   void Remove(u32 address);
 
   void Clear() { m_mem_checks.clear(); }
diff --git a/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp b/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
index 73c4cae584..62f78c7790 100644
--- a/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
+++ b/Source/Core/Core/PowerPC/Jit64Common/EmuCodeBlock.cpp
@@ -335,7 +335,7 @@ void EmuCodeBlock::MMIOLoadToReg(MMIO::Mapping* mmio, Gen::X64Reg reg_value,
 void EmuCodeBlock::SafeLoadToReg(X64Reg reg_value, const Gen::OpArg& opAddress, int accessSize,
                                  s32 offset, BitSet32 registersInUse, bool signExtend, int flags)
 {
-  bool slowmem = (flags & SAFE_LOADSTORE_FORCE_SLOWMEM) != 0 || g_jit->jo.alwaysUseMemFuncs;
+  bool slowmem = (flags & SAFE_LOADSTORE_FORCE_SLOWMEM) != 0;
 
   registersInUse[reg_value] = false;
   if (g_jit->jo.fastmem && !(flags & SAFE_LOADSTORE_NO_FASTMEM) && !slowmem)
@@ -492,7 +492,7 @@ void EmuCodeBlock::SafeWriteRegToReg(OpArg reg_value, X64Reg reg_addr, int acces
                                      BitSet32 registersInUse, int flags)
 {
   bool swap = !(flags & SAFE_LOADSTORE_NO_SWAP);
-  bool slowmem = (flags & SAFE_LOADSTORE_FORCE_SLOWMEM) != 0 || g_jit->jo.alwaysUseMemFuncs;
+  bool slowmem = (flags & SAFE_LOADSTORE_FORCE_SLOWMEM) != 0;
 
   // set the correct immediate format
   reg_value = FixImmediate(accessSize, reg_value);
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp b/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
index 455acf5cfe..9b0c837610 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
@@ -46,7 +46,6 @@ bool JitBase::MergeAllowedNextInstructions(int count)
 void JitBase::UpdateMemoryOptions()
 {
   bool any_watchpoints = PowerPC::memchecks.HasAny();
-  jo.fastmem = SConfig::GetInstance().bFastmem && !any_watchpoints;
+  jo.fastmem = SConfig::GetInstance().bFastmem && (UReg_MSR(MSR).DR || !any_watchpoints);
   jo.memcheck = SConfig::GetInstance().bMMU || any_watchpoints;
-  jo.alwaysUseMemFuncs = any_watchpoints;
 }
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitBase.h b/Source/Core/Core/PowerPC/JitCommon/JitBase.h
index c3c63dad41..f62776d6c3 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitBase.h
+++ b/Source/Core/Core/PowerPC/JitCommon/JitBase.h
@@ -52,7 +52,6 @@ protected:
     bool accurateSinglePrecision;
     bool fastmem;
     bool memcheck;
-    bool alwaysUseMemFuncs;
   };
   struct JitState
   {
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp b/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
index 54ce8c27f9..d04b4d22ac 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/JitCache.cpp
@@ -29,13 +29,6 @@
 
 using namespace Gen;
 
-static CoreTiming::EventType* s_clear_jit_cache_thread_safe;
-
-static void ClearCacheThreadSafe(u64 userdata, s64 cyclesdata)
-{
-  JitInterface::ClearCache();
-}
-
 bool JitBlock::OverlapsPhysicalRange(u32 address, u32 length) const
 {
   return physical_addresses.lower_bound(address) !=
@@ -50,7 +43,6 @@ JitBaseBlockCache::~JitBaseBlockCache() = default;
 
 void JitBaseBlockCache::Init()
 {
-  s_clear_jit_cache_thread_safe = CoreTiming::RegisterEvent("clearJitCache", ClearCacheThreadSafe);
   JitRegister::Init(SConfig::GetInstance().m_perfDir);
 
   Clear();
@@ -89,11 +81,6 @@ void JitBaseBlockCache::Reset()
   Init();
 }
 
-void JitBaseBlockCache::SchedulateClearCacheThreadSafe()
-{
-  CoreTiming::ScheduleEvent(0, s_clear_jit_cache_thread_safe, 0, CoreTiming::FromThread::NON_CPU);
-}
-
 JitBlock** JitBaseBlockCache::GetFastBlockMap()
 {
   return fast_block_map.data();
diff --git a/Source/Core/Core/PowerPC/JitCommon/JitCache.h b/Source/Core/Core/PowerPC/JitCommon/JitCache.h
index 485be781dd..76e2d4dbf9 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitCache.h
+++ b/Source/Core/Core/PowerPC/JitCommon/JitCache.h
@@ -125,7 +125,6 @@ public:
   void Shutdown();
   void Clear();
   void Reset();
-  void SchedulateClearCacheThreadSafe();
 
   // Code Cache
   JitBlock** GetFastBlockMap();
diff --git a/Source/Core/Core/PowerPC/MMU.cpp b/Source/Core/Core/PowerPC/MMU.cpp
index 416174a995..583d170f43 100644
--- a/Source/Core/Core/PowerPC/MMU.cpp
+++ b/Source/Core/Core/PowerPC/MMU.cpp
@@ -1191,6 +1191,10 @@ static void UpdateBATs(BatTable& bat_table, u32 base_spr)
           valid_bit = 0x3;
         else if ((address >> 28) == 0xE && (address < (0xE0000000 + Memory::L1_CACHE_SIZE)))
           valid_bit = 0x3;
+        // Fastmem doesn't support memchecks, so disable it for all overlapping virtual pages.
+        if (PowerPC::memchecks.OverlapsMemcheck(((batu.BEPI | j) << BAT_INDEX_SHIFT),
+                                                1 << BAT_INDEX_SHIFT))
+          valid_bit &= ~0x2;
 
         // (BEPI | j) == (BEPI & ~BL) | (j & BL).
         bat_table[batu.BEPI | j] = address | valid_bit;