diff --git a/Frameworks/lazyusf/lazyusf/main/main.c b/Frameworks/lazyusf/lazyusf/main/main.c
index b96ad28fa..4a35d2a18 100644
--- a/Frameworks/lazyusf/lazyusf/main/main.c
+++ b/Frameworks/lazyusf/lazyusf/main/main.c
@@ -137,7 +137,7 @@ m64p_error main_start(usf_state_t * state)
 #ifdef DEBUG_INFO
     state->r4300emu = 0;
 #else
-    state->r4300emu = state->enable_trimming_mode ? 1 : 2;
+    state->r4300emu = state->enable_trimming_mode ? 0 : 2;
 #endif
 
     /* set some other core parameters based on the config file values */
diff --git a/Frameworks/lazyusf/lazyusf/memory/memory.c b/Frameworks/lazyusf/lazyusf/memory/memory.c
index b9a318fc9..6cb530f66 100644
--- a/Frameworks/lazyusf/lazyusf/memory/memory.c
+++ b/Frameworks/lazyusf/lazyusf/memory/memory.c
@@ -23,6 +23,8 @@
 
 #include "usf/usf_internal.h"
 
+#include "usf/barray.h"
+
 #include "memory.h"
 
 #include "api/m64p_types.h"
@@ -1166,7 +1168,7 @@ int init_memory(usf_state_t * state, uint32_t rdram_size)
         map_region(state, 0xb000+i, M64P_MEM_NOTHING, RW(nothing));
     }
 
-    state->fast_memory = 1;
+    state->fast_memory = state->enable_trimming_mode ? 0 : 1;
 
     if (state->g_rom && state->g_rom_size >= 0xfc0)
         init_cic_using_ipl3(state, &state->g_si.pif.cic, state->g_rom + 0x40);
@@ -1241,6 +1243,24 @@ unsigned int * osal_fastcall fast_mem_access(usf_state_t * state, unsigned int a
 
     address &= 0x1ffffffc;
 
+    /* XXX this method is only valid for single 32 bit word fetches,
+     * as used by the pure interpreter CPU. The cached interpreter
+     * and the recompiler, on the other hand, fetch the start of a
+     * block and use the pointer for the entire block. */
+
+    if (state->enable_trimming_mode)
+    {
+        if (address < RDRAM_MAX_SIZE)
+        {
+            if (!bit_array_test(state->barray_ram_written_first, address / 4))
+                bit_array_set(state->barray_ram_read, address / 4);
+        }
+        else if ((address - 0x10000000) < state->g_rom_size)
+        {
+            bit_array_set(state->barray_rom, address / 4);
+        }
+    }
+
     if (address < RDRAM_MAX_SIZE)
         return (unsigned int*)((unsigned char*)state->g_rdram + address);
     else if (address >= 0x10000000)