diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index 12a420c2..211ecfec 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -100,7 +100,7 @@ terms of the MIT license. A copy of the license can be found in the file
 // Main tuning parameters for segment and page sizes
 // Sizes for 64-bit, divide by two for 32-bit
 #define MI_SEGMENT_SLICE_SHIFT            (13 + MI_INTPTR_SHIFT)         // 64kb
-#define MI_SEGMENT_SHIFT                  ( 8 + MI_SEGMENT_SLICE_SHIFT)  // 16mb
+#define MI_SEGMENT_SHIFT                  ( 7 + MI_SEGMENT_SLICE_SHIFT)  //  8mb
 
 #define MI_SMALL_PAGE_SHIFT               (MI_SEGMENT_SLICE_SHIFT)       // 64kb
 #define MI_MEDIUM_PAGE_SHIFT              ( 3 + MI_SMALL_PAGE_SHIFT)     // 512kb
diff --git a/src/arena.c b/src/arena.c
index b946ae64..351d9fb5 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -128,8 +128,8 @@ static bool mi_arena_alloc(mi_arena_t* arena, size_t blocks, mi_bitmap_index_t*
   Arena cache
 ----------------------------------------------------------- */
 
-#define MI_CACHE_FIELDS (8)
-#define MI_CACHE_MAX    (MI_BITMAP_FIELD_BITS*MI_CACHE_FIELDS)       // 512 on 64-bit
+#define MI_CACHE_FIELDS (16)
+#define MI_CACHE_MAX    (MI_BITMAP_FIELD_BITS*MI_CACHE_FIELDS)       // 1024 on 64-bit
 
 typedef struct mi_cache_slot_s {
   void*      p;
@@ -141,8 +141,8 @@ typedef struct mi_cache_slot_s {
 static mi_cache_slot_t cache[MI_CACHE_MAX];    // = 0
 
 #define BITS_SET()  (UINTPTR_MAX)
-static mi_bitmap_field_t cache_available[MI_CACHE_FIELDS] = { MI_INIT8(BITS_SET) };        // zero bit = available!
-static mi_bitmap_field_t cache_available_large[MI_CACHE_FIELDS] = { MI_INIT8(BITS_SET) };
+static mi_bitmap_field_t cache_available[MI_CACHE_FIELDS] = { MI_INIT16(BITS_SET) };        // zero bit = available!
+static mi_bitmap_field_t cache_available_large[MI_CACHE_FIELDS] = { MI_INIT16(BITS_SET) };
 static mi_bitmap_field_t cache_inuse[MI_CACHE_FIELDS];   // zero bit = free