diff --git a/src/common/memory_arena.cpp b/src/common/memory_arena.cpp
index 0b4d6e324..32acde32b 100644
--- a/src/common/memory_arena.cpp
+++ b/src/common/memory_arena.cpp
@@ -213,6 +213,15 @@ std::optional<MemoryArena::View> MemoryArena::CreateView(size_t offset, size_t s
   return View(this, base_pointer, offset, size, writable);
 }
 
+std::optional<MemoryArena::View> MemoryArena::CreateReservedView(size_t size, void* fixed_address /*= nullptr*/)
+{
+  void* base_pointer = CreateReservedPtr(size, fixed_address);
+  if (!base_pointer)
+    return std::nullopt;
+
+  return View(this, base_pointer, View::RESERVED_REGION_OFFSET, size, false);
+}
+
 void* MemoryArena::CreateViewPtr(size_t offset, size_t size, bool writable, bool executable,
                                  void* fixed_address /*= nullptr*/)
 {
@@ -276,6 +285,53 @@ bool MemoryArena::ReleaseViewPtr(void* address, size_t size)
   return true;
 }
 
+void* MemoryArena::CreateReservedPtr(size_t size, void* fixed_address /*= nullptr*/)
+{
+  void* base_pointer;
+#if defined(WIN32)
+  base_pointer = VirtualAlloc(fixed_address, size, MEM_RESERVE, PAGE_NOACCESS);
+#elif defined(__linux__)
+  const int flags =
+    (fixed_address != nullptr) ? (MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED) : (MAP_PRIVATE | MAP_ANONYMOUS);
+  base_pointer = mmap64(fixed_address, size, PROT_NONE, flags, -1, 0);
+  if (base_pointer == reinterpret_cast<void*>(-1))
+    return nullptr;
+#elif defined(__APPLE__) || defined(__FreeBSD__)
+  const int flags =
+    (fixed_address != nullptr) ? (MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED) : (MAP_PRIVATE | MAP_ANONYMOUS);
+  base_pointer = mmap(fixed_address, size, prot, PROT_NONE, -1, 0);
+  if (base_pointer == reinterpret_cast<void*>(-1))
+    return nullptr;
+#else
+  return nullptr;
+#endif
+
+  m_num_views.fetch_add(1);
+  return base_pointer;
+}
+
+bool MemoryArena::ReleaseReservedPtr(void* address, size_t size)
+{
+  bool result;
+#if defined(WIN32)
+  result = static_cast<bool>(VirtualFree(address, 0, MEM_RELEASE));
+#elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__)
+  result = (munmap(address, size) >= 0);
+#else
+  result = false;
+#endif
+
+  if (!result)
+  {
+    Log_ErrorPrintf("Failed to release previously-created view at %p", address);
+    return false;
+  }
+
+  const size_t prev_count = m_num_views.fetch_sub(1);
+  Assert(prev_count > 0);
+  return true;
+}
+
 bool MemoryArena::SetPageProtection(void* address, size_t length, bool readable, bool writable, bool executable)
 {
 #if defined(WIN32)
@@ -315,10 +371,18 @@ MemoryArena::View::~View()
 {
   if (m_parent)
   {
-    if (m_writable && !m_parent->FlushViewPtr(m_base_pointer, m_mapping_size))
-      Panic("Failed to flush previously-created view");
-    if (!m_parent->ReleaseViewPtr(m_base_pointer, m_mapping_size))
-      Panic("Failed to unmap previously-created view");
+    if (m_arena_offset != RESERVED_REGION_OFFSET)
+    {
+      if (m_writable && !m_parent->FlushViewPtr(m_base_pointer, m_mapping_size))
+        Panic("Failed to flush previously-created view");
+      if (!m_parent->ReleaseViewPtr(m_base_pointer, m_mapping_size))
+        Panic("Failed to unmap previously-created view");
+    }
+    else
+    {
+      if (!m_parent->ReleaseReservedPtr(m_base_pointer, m_mapping_size))
+        Panic("Failed to release previously-created view");
+    }
   }
 }
 } // namespace Common
diff --git a/src/common/memory_arena.h b/src/common/memory_arena.h
index 7e08f35ba..fee8ae214 100644
--- a/src/common/memory_arena.h
+++ b/src/common/memory_arena.h
@@ -10,6 +10,11 @@ public:
   class View
   {
   public:
+    enum : size_t
+    {
+      RESERVED_REGION_OFFSET = static_cast<size_t>(-1)
+    };
+
     View(MemoryArena* parent, void* base_pointer, size_t arena_offset, size_t mapping_size, bool writable);
     View(View&& view);
     ~View();
@@ -39,10 +44,15 @@ public:
   std::optional<View> CreateView(size_t offset, size_t size, bool writable, bool executable,
                                  void* fixed_address = nullptr);
 
+  std::optional<View> CreateReservedView(size_t size,  void* fixed_address = nullptr);
+
   void* CreateViewPtr(size_t offset, size_t size, bool writable, bool executable, void* fixed_address = nullptr);
   bool FlushViewPtr(void* address, size_t size);
   bool ReleaseViewPtr(void* address, size_t size);
 
+  void* CreateReservedPtr(size_t size, void* fixed_address = nullptr);
+  bool ReleaseReservedPtr(void* address, size_t size);
+
   static bool SetPageProtection(void* address, size_t length, bool readable, bool writable, bool executable);
 
 private:
diff --git a/src/core/bus.cpp b/src/core/bus.cpp
index 22509a157..3c592a3dc 100644
--- a/src/core/bus.cpp
+++ b/src/core/bus.cpp
@@ -95,6 +95,7 @@ static CPUFastmemMode m_fastmem_mode = CPUFastmemMode::Disabled;
 #ifdef WITH_MMAP_FASTMEM
 static u8* m_fastmem_base = nullptr;
 static std::vector<Common::MemoryArena::View> m_fastmem_ram_views;
+static std::vector<Common::MemoryArena::View> m_fastmem_reserved_views;
 #endif
 
 static u8** m_fastmem_lut = nullptr;
@@ -304,12 +305,18 @@ CPUFastmemMode GetFastmemMode()
   return m_fastmem_mode;
 }
 
-void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache)
+u8* GetFastmemBase()
+{
+  return m_fastmem_base;
+}
+
+void UpdateFastmemViews(CPUFastmemMode mode)
 {
 #ifndef WITH_MMAP_FASTMEM
   Assert(mode != CPUFastmemMode::MMap);
 #else
   m_fastmem_ram_views.clear();
+  m_fastmem_reserved_views.clear();
 #endif
 
   m_fastmem_mode = mode;
@@ -323,8 +330,6 @@ void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache)
     return;
   }
 
-  Log_DevPrintf("Remapping fastmem area, isolate cache = %s", isolate_cache ? "true" : "false");
-
 #ifdef WITH_MMAP_FASTMEM
   if (mode == CPUFastmemMode::MMap)
   {
@@ -344,9 +349,9 @@ void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache)
       CPU::g_state.fastmem_base = m_fastmem_base;
     }
 
-    auto MapRAM = [](u32 base_address, bool writable) {
+    auto MapRAM = [](u32 base_address) {
       u8* map_address = m_fastmem_base + base_address;
-      auto view = m_memory_arena.CreateView(MEMORY_ARENA_RAM_OFFSET, RAM_SIZE, writable, false, map_address);
+      auto view = m_memory_arena.CreateView(MEMORY_ARENA_RAM_OFFSET, RAM_SIZE, true, false, map_address);
       if (!view)
       {
         Log_ErrorPrintf("Failed to map RAM at fastmem area %p (offset 0x%08X)", map_address, RAM_SIZE);
@@ -370,26 +375,39 @@ void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache)
       m_fastmem_ram_views.push_back(std::move(view.value()));
     };
 
-    if (!isolate_cache)
-    {
-      // KUSEG - cached
-      MapRAM(0x00000000, true);
-      // MapRAM(0x00200000, true);
-      // MapRAM(0x00400000, true);
-      // MapRAM(0x00600000, true);
+    auto ReserveRegion = [](u32 start_address, u32 end_address_inclusive) {
+      Assert(end_address_inclusive >= start_address);
+      u8* map_address = m_fastmem_base + start_address;
+      auto view = m_memory_arena.CreateReservedView(end_address_inclusive - start_address + 1, map_address);
+      if (!view)
+      {
+        Log_ErrorPrintf("Failed to map RAM at fastmem area %p (offset 0x%08X)", map_address, RAM_SIZE);
+        return;
+      }
 
-      // KSEG0 - cached
-      MapRAM(0x80000000, true);
-      // MapRAM(0x80200000, true);
-      // MapRAM(0x80400000, true);
-      // MapRAM(0x80600000, true);
-    }
+      m_fastmem_reserved_views.push_back(std::move(view.value()));
+    };
+
+    // KUSEG - cached
+    MapRAM(0x00000000);
+    // MapRAM(0x00200000);
+    // MapRAM(0x00400000);
+    // MapRAM(0x00600000);
+    ReserveRegion(0x00200000, 0x80000000 - 1);
+
+    // KSEG0 - cached
+    MapRAM(0x80000000);
+    // MapRAM(0x80200000);
+    // MapRAM(0x80400000);
+    // MapRAM(0x80600000);
+    ReserveRegion(0x80200000, 0xA0000000 - 1);
 
     // KSEG1 - uncached
-    MapRAM(0xA0000000, true);
-    // MapRAM(0xA0200000, true);
-    // MapRAM(0xA0400000, true);
-    // MapRAM(0xA0600000, true);
+    MapRAM(0xA0000000);
+    // MapRAM(0xA0200000);
+    // MapRAM(0xA0400000);
+    // MapRAM(0xA0600000);
+    ReserveRegion(0xA0200000, 0xFFFFFFFF);
 
     return;
   }
@@ -408,39 +426,31 @@ void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache)
     CPU::g_state.fastmem_base = reinterpret_cast<u8*>(m_fastmem_lut);
   }
 
-  auto MapRAM = [](u32 base_address, bool readable, bool writable) {
-    if (readable)
+  auto MapRAM = [](u32 base_address) {
+    for (u32 address = 0; address < RAM_SIZE; address += HOST_PAGE_SIZE)
     {
-      for (u32 address = 0; address < RAM_SIZE; address += HOST_PAGE_SIZE)
-      {
-        SetLUTFastmemPage(base_address + address, &g_ram[address],
-                          !m_ram_code_bits[FastmemAddressToLUTPageIndex(address)]);
-      }
-    }
-    else
-    {
-      for (u32 address = 0; address < RAM_SIZE; address += HOST_PAGE_SIZE)
-        SetLUTFastmemPage(base_address + address, nullptr, false);
+      SetLUTFastmemPage(base_address + address, &g_ram[address],
+                        !m_ram_code_bits[FastmemAddressToLUTPageIndex(address)]);
     }
   };
 
   // KUSEG - cached
-  MapRAM(0x00000000, !isolate_cache, !isolate_cache);
-  MapRAM(0x00200000, !isolate_cache, !isolate_cache);
-  MapRAM(0x00400000, !isolate_cache, !isolate_cache);
-  MapRAM(0x00600000, !isolate_cache, !isolate_cache);
+  MapRAM(0x00000000);
+  MapRAM(0x00200000);
+  MapRAM(0x00400000);
+  MapRAM(0x00600000);
 
   // KSEG0 - cached
-  MapRAM(0x80000000, !isolate_cache, !isolate_cache);
-  MapRAM(0x80200000, !isolate_cache, !isolate_cache);
-  MapRAM(0x80400000, !isolate_cache, !isolate_cache);
-  MapRAM(0x80600000, !isolate_cache, !isolate_cache);
+  MapRAM(0x80000000);
+  MapRAM(0x80200000);
+  MapRAM(0x80400000);
+  MapRAM(0x80600000);
 
   // KSEG1 - uncached
-  MapRAM(0xA0000000, true, true);
-  MapRAM(0xA0200000, true, true);
-  MapRAM(0xA0400000, true, true);
-  MapRAM(0xA0600000, true, true);
+  MapRAM(0xA0000000);
+  MapRAM(0xA0200000);
+  MapRAM(0xA0400000);
+  MapRAM(0xA0600000);
 }
 
 bool CanUseFastmemForAddress(VirtualMemoryAddress address)
diff --git a/src/core/bus.h b/src/core/bus.h
index 2968a0945..228962113 100644
--- a/src/core/bus.h
+++ b/src/core/bus.h
@@ -100,7 +100,8 @@ void Reset();
 bool DoState(StateWrapper& sw);
 
 CPUFastmemMode GetFastmemMode();
-void UpdateFastmemViews(CPUFastmemMode mode, bool isolate_cache);
+u8* GetFastmemBase();
+void UpdateFastmemViews(CPUFastmemMode mode);
 bool CanUseFastmemForAddress(VirtualMemoryAddress address);
 
 void SetExpansionROM(std::vector<u8> data);
diff --git a/src/core/cpu_code_cache.cpp b/src/core/cpu_code_cache.cpp
index ae9278626..f160807c6 100644
--- a/src/core/cpu_code_cache.cpp
+++ b/src/core/cpu_code_cache.cpp
@@ -784,14 +784,14 @@ bool InitializeFastmem()
     return false;
   }
 
-  Bus::UpdateFastmemViews(mode, g_state.cop0_regs.sr.Isc);
+  Bus::UpdateFastmemViews(mode);
   return true;
 }
 
 void ShutdownFastmem()
 {
   Common::PageFaultHandler::RemoveHandler(&s_host_code_map);
-  Bus::UpdateFastmemViews(CPUFastmemMode::Disabled, false);
+  Bus::UpdateFastmemViews(CPUFastmemMode::Disabled);
 }
 
 #ifdef WITH_MMAP_FASTMEM
diff --git a/src/core/cpu_core.cpp b/src/core/cpu_core.cpp
index 890c1f282..4c5d7fb0d 100644
--- a/src/core/cpu_core.cpp
+++ b/src/core/cpu_core.cpp
@@ -1975,7 +1975,10 @@ bool InterpretInstructionPGXP()
 
 void UpdateFastmemMapping()
 {
-  Bus::UpdateFastmemViews(Bus::GetFastmemMode(), g_state.cop0_regs.sr.Isc);
+  if (g_state.cop0_regs.sr.Isc)
+    g_state.fastmem_base = nullptr;
+  else
+    g_state.fastmem_base = Bus::GetFastmemBase();
 }
 
 } // namespace Recompiler::Thunks
diff --git a/src/core/cpu_recompiler_code_generator.cpp b/src/core/cpu_recompiler_code_generator.cpp
index b5450317f..c44a6860c 100644
--- a/src/core/cpu_recompiler_code_generator.cpp
+++ b/src/core/cpu_recompiler_code_generator.cpp
@@ -2476,6 +2476,7 @@ bool CodeGenerator::Compile_cop0(const CodeBlockInstruction& cbi)
               EmitBranchIfBitClear(old_value.host_reg, RegSize_32, 16, &skip_fastmem_update);
               m_register_cache.InhibitAllocation();
               EmitFunctionCall(nullptr, &Thunks::UpdateFastmemMapping, m_register_cache.GetCPUPtr());
+              EmitUpdateMembasePointer();
               EmitBindLabel(&skip_fastmem_update);
               m_register_cache.UninhibitAllocation();
             }
diff --git a/src/core/cpu_recompiler_code_generator.h b/src/core/cpu_recompiler_code_generator.h
index e07470e79..21c007449 100644
--- a/src/core/cpu_recompiler_code_generator.h
+++ b/src/core/cpu_recompiler_code_generator.h
@@ -93,6 +93,7 @@ public:
   void EmitStoreGuestMemoryFastmem(const CodeBlockInstruction& cbi, const Value& address, const Value& value);
   void EmitStoreGuestMemorySlowmem(const CodeBlockInstruction& cbi, const Value& address, const Value& value,
                                    bool in_far_code);
+  void EmitUpdateMembasePointer();
 
   // Unconditional branch to pointer. May allocate a scratch register.
   void EmitBranch(const void* address, bool allow_scratch = true);
diff --git a/src/core/cpu_recompiler_code_generator_aarch32.cpp b/src/core/cpu_recompiler_code_generator_aarch32.cpp
index 8d217cc5e..bbee08222 100644
--- a/src/core/cpu_recompiler_code_generator_aarch32.cpp
+++ b/src/core/cpu_recompiler_code_generator_aarch32.cpp
@@ -1170,6 +1170,22 @@ Value CodeGenerator::GetFastmemStoreBase()
   return val;
 }
 
+void CodeGenerator::EmitUpdateMembasePointer()
+{
+  if (m_fastmem_load_base_in_register)
+  {
+    Value val = Value::FromHostReg(&m_register_cache, RARG4, RegSize_32);
+    m_emit->ldr(GetHostReg32(val), a32::MemOperand(GetCPUPtrReg(), offsetof(CPU::State, fastmem_base)));
+  }
+
+  if (m_fastmem_store_base_in_register)
+  {
+    Value val = Value::FromHostReg(&m_register_cache, RARG3, RegSize_32);
+    m_emit->ldr(GetHostReg32(val), a32::MemOperand(GetCPUPtrReg(), offsetof(CPU::State, fastmem_base)));
+    m_emit->add(GetHostReg32(val), GetHostReg32(val), sizeof(u32*) * Bus::FASTMEM_LUT_NUM_PAGES);
+  }
+}
+
 void CodeGenerator::EmitLoadGuestRAMFastmem(const Value& address, RegSize size, Value& result)
 {
   Value fastmem_base = GetFastmemLoadBase();
diff --git a/src/core/cpu_recompiler_code_generator_aarch64.cpp b/src/core/cpu_recompiler_code_generator_aarch64.cpp
index 5becc679a..1e3664266 100644
--- a/src/core/cpu_recompiler_code_generator_aarch64.cpp
+++ b/src/core/cpu_recompiler_code_generator_aarch64.cpp
@@ -1728,6 +1728,11 @@ void CodeGenerator::EmitStoreGuestMemorySlowmem(const CodeBlockInstruction& cbi,
   }
 }
 
+void CodeGenerator::EmitUpdateMembasePointer()
+{
+  m_emit->Ldr(GetFastmemBasePtrReg(), a64::MemOperand(GetCPUPtrReg(), offsetof(State, fastmem_base)));
+}
+
 bool CodeGenerator::BackpatchLoadStore(const LoadStoreBackpatchInfo& lbi)
 {
   Log_DevPrintf("Backpatching %p (guest PC 0x%08X) to slowmem at %p", lbi.host_pc, lbi.guest_pc, lbi.host_slowmem_pc);
diff --git a/src/core/cpu_recompiler_code_generator_x64.cpp b/src/core/cpu_recompiler_code_generator_x64.cpp
index eb740b443..d782cac64 100644
--- a/src/core/cpu_recompiler_code_generator_x64.cpp
+++ b/src/core/cpu_recompiler_code_generator_x64.cpp
@@ -2313,6 +2313,11 @@ void CodeGenerator::EmitStoreGuestMemorySlowmem(const CodeBlockInstruction& cbi,
   }
 }
 
+void CodeGenerator::EmitUpdateMembasePointer()
+{
+  m_emit->mov(GetFastmemBasePtrReg(), m_emit->qword[GetCPUPtrReg() + offsetof(CPU::State, fastmem_base)]);
+}
+
 bool CodeGenerator::BackpatchLoadStore(const LoadStoreBackpatchInfo& lbi)
 {
   Log_DevPrintf("Backpatching %p (guest PC 0x%08X) to slowmem", lbi.host_pc, lbi.guest_pc);
diff --git a/src/core/host_interface.cpp b/src/core/host_interface.cpp
index 6bd71b512..da4198ab8 100644
--- a/src/core/host_interface.cpp
+++ b/src/core/host_interface.cpp
@@ -801,9 +801,6 @@ void HostInterface::CheckForSettingsChanges(const Settings& old_settings)
         g_settings.rewind_enable != old_settings.rewind_enable ||
         g_settings.runahead_frames != old_settings.runahead_frames)
     {
-      if (g_settings.IsUsingCodeCache())
-        CPU::CodeCache::Reinitialize();
-
       g_gpu->UpdateSettings();
     }
 
diff --git a/src/core/system.cpp b/src/core/system.cpp
index 78162699c..3693c39d6 100644
--- a/src/core/system.cpp
+++ b/src/core/system.cpp
@@ -679,9 +679,6 @@ bool RecreateGPU(GPURenderer renderer, bool update_display /* = true*/)
     return false;
   }
 
-  // reinitialize the code cache because the address space could change
-  CPU::CodeCache::Reinitialize();
-
   if (state_valid)
   {
     state_stream->SeekAbsolute(0);
@@ -1940,10 +1937,6 @@ bool InsertMedia(const char* path)
     UpdateMemoryCards();
   }
 
-  // reinitialize recompiler, because especially with preloading this might overlap the fastmem area
-  if (g_settings.IsUsingCodeCache())
-    CPU::CodeCache::Reinitialize();
-
   ClearMemorySaveStates();
   return true;
 }
@@ -2069,10 +2062,6 @@ bool SwitchMediaSubImage(u32 index)
     image->GetSubImageMetadata(index, "title").c_str(), index + 1u, image->GetMetadata("title").c_str());
   g_cdrom.InsertMedia(std::move(image));
 
-  // reinitialize recompiler, because especially with preloading this might overlap the fastmem area
-  if (g_settings.IsUsingCodeCache())
-    CPU::CodeCache::Reinitialize();
-
   ClearMemorySaveStates();
   return true;
 }