diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index a5fd12b8..6685b5a7 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -89,7 +89,7 @@ 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                  (10 + MI_SEGMENT_SLICE_SHIFT)  // 64mb
+#define MI_SEGMENT_SHIFT                  ( 8 + MI_SEGMENT_SLICE_SHIFT)  // 64mb
 
 #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/alloc.c b/src/alloc.c
index de8bd3d2..6370b19d 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -195,6 +195,7 @@ static mi_decl_noinline void mi_free_huge_block_mt(mi_segment_t* segment, mi_pag
     mi_tld_t* tld = heap->tld;
     const size_t bsize = mi_page_block_size(page);
     if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+      mi_assert_internal(false);
       _mi_stat_decrease(&tld->stats.large, bsize);
     }
     else {
diff --git a/src/arena.c b/src/arena.c
index 104a7e83..4fb1364a 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -1,3 +1,4 @@
+
 /* ----------------------------------------------------------------------------
 Copyright (c) 2019, Microsoft Research, Daan Leijen
 This is free software; you can redistribute it and/or modify it under the
@@ -36,7 +37,8 @@ of 256MiB in practice.
 
 // os.c
 void* _mi_os_alloc_aligned(size_t size, size_t alignment, bool commit, bool* large, mi_os_tld_t* tld);
-void  _mi_os_free(void* p, size_t size, mi_stats_t* stats);
+// void  _mi_os_free(void* p, size_t size, mi_stats_t* stats);
+void  _mi_os_free_ex(void* p, size_t size, bool was_committed, mi_stats_t* stats);
 
 void* _mi_os_alloc_huge_os_pages(size_t pages, int numa_node, mi_msecs_t max_secs, size_t* pages_reserved, size_t* psize);
 void  _mi_os_free_huge_pages(void* p, size_t size, mi_stats_t* stats);
@@ -178,8 +180,11 @@ static void* mi_cache_pop(int numa_node, size_t size, size_t alignment, bool* co
             if (*commit && !committed) {
               bool commit_zero;
               _mi_os_commit(p, MI_SEGMENT_SIZE, &commit_zero, tld->stats);
+              *commit = true;
             }            
-            *commit = committed;
+            else {
+              *commit = committed;
+            }
             return p;
           }
         }
@@ -207,7 +212,7 @@ static void mi_cache_purge(mi_os_tld_t* tld) {
         // expired, try to claim it
         if (mi_atomic_cas_ptr_weak(&slot->p, MI_SLOT_IN_USE, p)) {
           // claimed! test again
-          if (!slot->is_committed && !slot->is_large && now >= slot->expire) {
+          if (slot->is_committed && !slot->is_large && now >= slot->expire) {
             _mi_os_decommit(p, MI_SEGMENT_SIZE, tld->stats);
             slot->is_committed = false;
           }
@@ -239,15 +244,20 @@ static bool mi_cache_push(void* start, size_t size, size_t memid, bool is_commit
     if (p == NULL) { // free slot
       if (mi_atomic_cas_ptr_weak(&slot->p, MI_SLOT_IN_USE, NULL)) {
         // claimed!
-        long delay = mi_option_get(mi_option_arena_reset_delay);
-        if (delay == 0 && !is_large) {
-          _mi_os_decommit(start, size, tld->stats);
-          is_committed = false;
-        }
-        slot->expire = (is_committed ? 0 : _mi_clock_now() + delay);
+        slot->expire = 0;
         slot->is_committed = is_committed;
         slot->memid = memid;
         slot->is_large = is_large;
+        if (is_committed) {
+          long delay = mi_option_get(mi_option_arena_reset_delay);
+          if (delay == 0 && !is_large) {
+            _mi_os_decommit(start, size, tld->stats);
+            slot->is_committed = false;
+          }
+          else {
+            slot->expire = _mi_clock_now() + delay;
+          }
+        }
         mi_atomic_write_ptr(&slot->p, start); // and make it available;
         return true;
       }
@@ -369,7 +379,7 @@ void _mi_arena_free(void* p, size_t size, size_t memid, bool is_committed, bool
   if (memid == MI_MEMID_OS) {
     // was a direct OS allocation, pass through
     if (!mi_cache_push(p, size, memid, is_committed, is_large, tld)) {
-      _mi_os_free(p, size, tld->stats);
+      _mi_os_free_ex(p, size, is_committed, tld->stats);
     }
   }
   else {
diff --git a/src/options.c b/src/options.c
index 489f07b3..1130e2e3 100644
--- a/src/options.c
+++ b/src/options.c
@@ -71,7 +71,7 @@ static mi_option_desc_t options[_mi_option_last] =
   { 0, UNINIT, MI_OPTION(abandoned_page_reset) },// reset free page memory when a thread terminates
   { 0, UNINIT, MI_OPTION(segment_reset) },       // reset segment memory on free (needs eager commit)
   { 0, UNINIT, MI_OPTION(eager_commit_delay) },  // the first N segments per thread are not eagerly committed
-  { 0, UNINIT, MI_OPTION(allow_decommit) },      // decommit pages when not eager committed
+  { 1, UNINIT, MI_OPTION(allow_decommit) },      // decommit pages when not eager committed
   { 100,  UNINIT, MI_OPTION(reset_delay) },       // reset delay in milli-seconds
   { 1000, UNINIT, MI_OPTION(arena_reset_delay) }, // reset delay in milli-seconds
   { 0,    UNINIT, MI_OPTION(use_numa_nodes) },    // 0 = use available numa nodes, otherwise use at most N nodes. 
diff --git a/src/page.c b/src/page.c
index 44f32a73..13706100 100644
--- a/src/page.c
+++ b/src/page.c
@@ -378,9 +378,22 @@ void _mi_page_free(mi_page_t* page, mi_page_queue_t* pq, bool force) {
   // no more aligned blocks in here
   mi_page_set_has_aligned(page, false);
 
+  mi_heap_t* heap = mi_page_heap(page);
+  const size_t bsize = mi_page_block_size(page);
+  if (bsize > MI_MEDIUM_OBJ_SIZE_MAX) {
+    if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {      
+      _mi_stat_decrease(&heap->tld->stats.large, bsize);
+    }
+    else {
+      // not strictly necessary as we never get here for a huge page
+      mi_assert_internal(false);
+      _mi_stat_decrease(&heap->tld->stats.huge, bsize);      
+    }
+  }
+
   // remove from the page list
   // (no need to do _mi_heap_delayed_free first as all blocks are already free)
-  mi_segments_tld_t* segments_tld = &mi_page_heap(page)->tld->segments;
+  mi_segments_tld_t* segments_tld = &heap->tld->segments;
   mi_page_queue_remove(pq, page);
 
   // and free it
@@ -769,11 +782,11 @@ static mi_page_t* mi_large_huge_page_alloc(mi_heap_t* heap, size_t size) {
       mi_assert_internal(_mi_page_segment(page)->kind != MI_SEGMENT_HUGE);
     }
     if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
-      _mi_stat_increase(&heap->tld->stats.large, block_size);
+      _mi_stat_increase(&heap->tld->stats.large, bsize);
       _mi_stat_counter_increase(&heap->tld->stats.large_count, 1);
     }
     else {
-      _mi_stat_increase(&heap->tld->stats.huge, block_size);
+      _mi_stat_increase(&heap->tld->stats.huge, bsize);
       _mi_stat_counter_increase(&heap->tld->stats.huge_count, 1);
     }
   }
diff --git a/src/segment.c b/src/segment.c
index 5ce4d7ba..b3a33d60 100644
--- a/src/segment.c
+++ b/src/segment.c
@@ -7,6 +7,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #include "mimalloc.h"
 #include "mimalloc-internal.h"
 #include "mimalloc-atomic.h"
+#include "bitmap.inc.c"  // mi_bsr
 
 #include <string.h>  // memset
 #include <stdio.h>
@@ -49,23 +50,7 @@ static uint8_t* mi_slice_start(const mi_slice_t* slice) {
    Bins
 ----------------------------------------------------------- */
 // Use bit scan forward to quickly find the first zero bit if it is available
-#if defined(_MSC_VER)
-#include <intrin.h>
-static inline size_t mi_bsr(uintptr_t x) {
-  if (x==0) return 8*MI_INTPTR_SIZE;
-  DWORD idx;
-  #if (MI_INTPTR_SIZE==8)
-  _BitScanReverse64(&idx, x);
-  #else
-  _BitScanReverse(&idx, x);
-  #endif
-  return idx;
-}
-#elif defined(__GNUC__) || defined(__clang__)
-static inline size_t mi_bsr(uintptr_t x) {
-  return (x==0 ? 8*MI_INTPTR_SIZE : (8*MI_INTPTR_SIZE - 1) - __builtin_clzl(x));
-}
-#else
+#if !defined(MI_HAVE_BITSCAN)
 #error "define bsr for your platform"
 #endif
 
@@ -410,7 +395,7 @@ static void mi_segment_commitx(mi_segment_t* segment, bool commit, uint8_t* p, s
   }
   else if (!commit && (segment->commit_mask & mask) != 0) {
     mi_assert_internal((void*)start != (void*)segment);
-    _mi_os_decommit(start, full_size,stats);
+    _mi_os_decommit(start, full_size, stats);
     segment->commit_mask &= ~mask;
   }
   // increase expiration of reusing part of the delayed decommit
@@ -902,8 +887,8 @@ static void mi_segment_abandon(mi_segment_t* segment, mi_segments_tld_t* tld) {
     slice = slice + slice->slice_count;
   }
 
-  // force delayed decommits instead?
-  mi_segment_delayed_decommit(segment, false, tld->stats);    
+  // perform delayed decommits instead
+  mi_segment_delayed_decommit(segment, mi_option_is_enabled(mi_option_abandoned_page_reset), tld->stats);    
   
   // all pages in the segment are abandoned; add it to the abandoned list
   _mi_stat_increase(&tld->stats->segments_abandoned, 1);
@@ -1018,7 +1003,7 @@ bool _mi_segment_try_reclaim_abandoned( mi_heap_t* heap, bool try_all, mi_segmen
     if (segment->used == 0) {  // due to page_clear
       mi_segment_free(segment,false,tld);
     }
-    
+
     // go on
     segment = next; 
   }
@@ -1185,6 +1170,5 @@ static void* mi_segment_range_of(const void* p, size_t* size) {
   mi_reset_delayed(tld);
   mi_assert_internal(page == NULL || mi_page_not_in_queue(page, tld));
   return page;
->>>>>>> dev
 }
 */
diff --git a/src/static.c b/src/static.c
index bcfaa119..b3c71e02 100644
--- a/src/static.c
+++ b/src/static.c
@@ -16,12 +16,8 @@ terms of the MIT license. A copy of the license can be found in the file
 #include "stats.c"
 #include "random.c"
 #include "os.c"
-<<<<<<< HEAD
 //#include "memory.c"
-=======
 #include "arena.c"
-#include "memory.c"
->>>>>>> dev
 #include "segment.c"
 #include "page.c"
 #include "heap.c"