diff --git a/core/box/warm_pool_prefill_box.h b/core/box/warm_pool_prefill_box.h
index 9191c336..89769c65 100644
--- a/core/box/warm_pool_prefill_box.h
+++ b/core/box/warm_pool_prefill_box.h
@@ -24,7 +24,8 @@ extern SuperSlab* superslab_refill(int class_idx);
 // Prefill budget: How many additional SuperSlabs to load when pool is empty
 // - If pool is empty, load PREFILL_BUDGET extra slabs to build working set
 // - This avoids repeated registry scans on rapid cache misses
-#define WARM_POOL_PREFILL_BUDGET 3
+// - Set to 2 to balance between prefill lock overhead and pool depletion
+#define WARM_POOL_PREFILL_BUDGET 2
 
 // ============================================================================
 // Warm Pool Prefill API (Inline for Cold Path)
diff --git a/core/box/warm_pool_stats_box.h b/core/box/warm_pool_stats_box.h
index 3556e929..519e5418 100644
--- a/core/box/warm_pool_stats_box.h
+++ b/core/box/warm_pool_stats_box.h
@@ -23,19 +23,31 @@ extern __thread TinyWarmPoolStats g_warm_pool_stats[TINY_NUM_CLASSES];
 // Record a warm pool hit
 // Called when warm_pool_pop() succeeds and carve produces blocks
 static inline void warm_pool_record_hit(int class_idx) {
+#if HAKMEM_DEBUG_COUNTERS
     g_warm_pool_stats[class_idx].hits++;
+#else
+    (void)class_idx;
+#endif
 }
 
 // Record a warm pool miss
 // Called when warm_pool_pop() returns NULL (pool empty)
 static inline void warm_pool_record_miss(int class_idx) {
+#if HAKMEM_DEBUG_COUNTERS
     g_warm_pool_stats[class_idx].misses++;
+#else
+    (void)class_idx;
+#endif
 }
 
 // Record a warm pool prefill event
 // Called when pool is empty and we do secondary prefill
 static inline void warm_pool_record_prefilled(int class_idx) {
+#if HAKMEM_DEBUG_COUNTERS
     g_warm_pool_stats[class_idx].prefilled++;
+#else
+    (void)class_idx;
+#endif
 }
 
 #endif // HAK_WARM_POOL_STATS_BOX_H
diff --git a/core/front/tiny_unified_cache.c b/core/front/tiny_unified_cache.c
index c49694c9..5fd29ed7 100644
--- a/core/front/tiny_unified_cache.c
+++ b/core/front/tiny_unified_cache.c
@@ -497,7 +497,8 @@ hak_base_ptr_t unified_cache_refill(int class_idx) {
             // Freelist pop
             void* p = m->freelist;
 
-            // Validate freelist head before dereferencing
+            // Validate freelist head before dereferencing (only in debug builds)
+            #if !HAKMEM_BUILD_RELEASE
             do {
                 SuperSlab* fl_ss = hak_super_lookup(p);
                 int fl_cap = fl_ss ? ss_slabs_capacity(fl_ss) : 0;
@@ -525,6 +526,7 @@ hak_base_ptr_t unified_cache_refill(int class_idx) {
                     p = NULL;
                 }
             } while (0);
+            #endif
             if (!p) {
                 break;
             }
diff --git a/core/hakmem_build_flags.h b/core/hakmem_build_flags.h
index 5e94b3cd..8a414861 100644
--- a/core/hakmem_build_flags.h
+++ b/core/hakmem_build_flags.h
@@ -30,8 +30,13 @@
 // Instrumentation & counters (compile-time)
 // ------------------------------------------------------------
 // Enable lightweight path/debug counters (compiled out when 0)
+// Default: 0 in release builds (NDEBUG set), 1 in debug builds
 #ifndef HAKMEM_DEBUG_COUNTERS
-#  define HAKMEM_DEBUG_COUNTERS 1
+#  if defined(NDEBUG)
+#    define HAKMEM_DEBUG_COUNTERS 0
+#  else
+#    define HAKMEM_DEBUG_COUNTERS 1
+#  endif
 #endif
 
 // Enable extended memory profiling (compiled out when 0)