diff --git a/Source/Core/Core/PowerPC/BreakPoints.cpp b/Source/Core/Core/PowerPC/BreakPoints.cpp
index 6bca42b4b3..8714efda87 100644
--- a/Source/Core/Core/PowerPC/BreakPoints.cpp
+++ b/Source/Core/Core/PowerPC/BreakPoints.cpp
@@ -173,8 +173,8 @@ void MemChecks::Add(const TMemCheck& memory_check)
   if (GetMemCheck(memory_check.start_address) == nullptr)
   {
     bool had_any = HasAny();
-    m_mem_checks.push_back(memory_check);
     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)
@@ -190,8 +190,8 @@ void MemChecks::Remove(u32 address)
   {
     if (i->start_address == address)
     {
-      m_mem_checks.erase(i);
       bool lock = Core::PauseAndLock(true);
+      m_mem_checks.erase(i);
       if (!HasAny() && g_jit)
         g_jit->ClearCache();
       PowerPC::DBATUpdated();
@@ -220,6 +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/JitCommon/JitBase.cpp b/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
index 0b047fca97..9b0c837610 100644
--- a/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/JitBase.cpp
@@ -46,6 +46,6 @@ bool JitBase::MergeAllowedNextInstructions(int count)
 void JitBase::UpdateMemoryOptions()
 {
   bool any_watchpoints = PowerPC::memchecks.HasAny();
-  jo.fastmem = SConfig::GetInstance().bFastmem;
+  jo.fastmem = SConfig::GetInstance().bFastmem && (UReg_MSR(MSR).DR || !any_watchpoints);
   jo.memcheck = SConfig::GetInstance().bMMU || any_watchpoints;
 }
diff --git a/Source/Core/Core/PowerPC/MMU.cpp b/Source/Core/Core/PowerPC/MMU.cpp
index 992af28ac7..583d170f43 100644
--- a/Source/Core/Core/PowerPC/MMU.cpp
+++ b/Source/Core/Core/PowerPC/MMU.cpp
@@ -1132,24 +1132,6 @@ static TranslateAddressResult TranslatePageAddress(const u32 address, const XChe
   return TranslateAddressResult{TranslateAddressResult::PAGE_FAULT, 0};
 }
 
-static bool overlaps_memcheck(u32 pageEndAddress)
-{
-  if (!memchecks.HasAny())
-    return false;
-  u32 page_end_suffix = ((1 << BAT_INDEX_SHIFT)) - 1;
-  for (TMemCheck memcheck : memchecks.GetMemChecks())
-  {
-    if (((memcheck.start_address | page_end_suffix) == pageEndAddress ||
-         (memcheck.end_address | page_end_suffix) == pageEndAddress) ||
-        ((memcheck.start_address | page_end_suffix) < pageEndAddress &&
-         (memcheck.end_address | page_end_suffix) > pageEndAddress))
-    {
-      return true;
-    }
-  }
-  return false;
-}
-
 static void UpdateBATs(BatTable& bat_table, u32 base_spr)
 {
   // TODO: Separate BATs for MSR.PR==0 and MSR.PR==1
@@ -1209,7 +1191,9 @@ 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;
-        if (overlaps_memcheck(((batu.BEPI | j) << BAT_INDEX_SHIFT) | ((1 << BAT_INDEX_SHIFT) - 1)))
+        // 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).