diff --git a/include/sys/kmem.h b/include/sys/kmem.h
index 1dfc0bf1e..319c800b6 100644
--- a/include/sys/kmem.h
+++ b/include/sys/kmem.h
@@ -5,7 +5,8 @@
 extern "C" {
 #endif
 
-#define DEBUG_KMEM
+//#define DEBUG_KMEM
+#undef DEBUG_KMEM
 #undef DEBUG_KMEM_UNIMPLEMENTED
 
 #include <linux/module.h>
@@ -247,30 +248,25 @@ __kmem_del_init(spinlock_t *lock,struct hlist_head *table,int bits,void *addr)
         vfree(ptr);                                                           \
 })
 
-#else
+#else /* DEBUG_KMEM */
 
 #define kmem_alloc(size, flags)         kmalloc((size), (flags))
 #define kmem_zalloc(size, flags)        kzalloc((size), (flags))
-#define kmem_free(ptr, size)                                                  \
-({                                                                            \
-        ASSERT((ptr) || (size > 0));                                          \
-	kfree(ptr);                                                           \
-})
+#define kmem_free(ptr, size)            kfree(ptr)
 
 #define vmem_alloc(size, flags)         __vmalloc((size), ((flags) |          \
-						  __GFP_HIGHMEM), PAGE_KERNEL)
-#define vmem_zalloc(size, flags)        __vmalloc((size), ((flags) |          \
-						  __GFP_HIGHMEM | __GFP_ZERO) \
-						  PAGE_KERNEL)
-#define vmem_free(ptr, size)                                                  \
+					__GFP_HIGHMEM), PAGE_KERNEL)
+#define vmem_zalloc(size, flags)                                              \
 ({                                                                            \
-        ASSERT((ptr) || (size > 0));                                          \
-	vfree(ptr);                                                           \
+        void *_ptr_ = __vmalloc((size),((flags)|__GFP_HIGHMEM),PAGE_KERNEL);  \
+        if (_ptr_)                                                            \
+                memset(_ptr_, 0, (size));                                     \
+        _ptr_;                                                                \
 })
+#define vmem_free(ptr, size)            vfree(ptr)
 
 #endif /* DEBUG_KMEM */
 
-
 #ifdef DEBUG_KMEM_UNIMPLEMENTED
 static __inline__ void *
 kmem_alloc_tryhard(size_t size, size_t *alloc_size, int kmflags)
diff --git a/include/sys/mutex.h b/include/sys/mutex.h
index 58d1bf629..b54f495b9 100644
--- a/include/sys/mutex.h
+++ b/include/sys/mutex.h
@@ -10,7 +10,8 @@ extern "C" {
 #include <sys/types.h>
 #include <sys/kmem.h>
 
-#define DEBUG_MUTEX
+//#define DEBUG_MUTEX
+#undef DEBUG_MUTEX
 
 #define MUTEX_DEFAULT		0
 #define MUTEX_SPIN		1
diff --git a/modules/spl/spl-kmem.c b/modules/spl/spl-kmem.c
index 80c4488b1..f82c1c240 100644
--- a/modules/spl/spl-kmem.c
+++ b/modules/spl/spl-kmem.c
@@ -378,7 +378,9 @@ __kmem_cache_alloc(kmem_cache_t *cache, gfp_t flags)
 restart:
 	rc = kmem_cache_alloc(cache, flags);
         if ((rc == NULL) && (flags & KM_SLEEP)) {
+#ifdef DEBUG_KMEM
 		atomic64_inc(&kmem_cache_alloc_failed);
+#endif /* DEBUG_KMEM */
 		GOTO(restart, rc);
 	}
 
@@ -428,7 +430,9 @@ kmem_init(void)
 	RETURN(0);
 }
 
-static char *sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
+#ifdef DEBUG_KMEM
+static char *
+sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
 {
         int size = ((len - 1) < kd->kd_size) ? (len - 1) : kd->kd_size;
 	int i, flag = 1;
@@ -468,6 +472,7 @@ static char *sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
 
 	return str;
 }
+#endif /* DEBUG_KMEM */
 
 void
 kmem_fini(void)
diff --git a/modules/spl/spl-mutex.c b/modules/spl/spl-mutex.c
index 1eabda610..d9f3c0759 100644
--- a/modules/spl/spl-mutex.c
+++ b/modules/spl/spl-mutex.c
@@ -88,6 +88,12 @@ __spl_mutex_init(kmutex_t *mp, char *name, int type, void *ibc)
 		return;
 	}
 
+	/* XXX - This appears to be a much more contended lock than I
+	 * would have expected.  To run with this debugging enabled and
+	 * get reasonable performance we may need to be more clever and
+	 * do something like hash the mutex ptr on to one of several
+	 * lists to ease this single point of contention.
+	 */
 	spin_lock(&mutex_stats_lock);
 	list_add_tail(&mp->km_list, &mutex_stats_list);
 	spin_unlock(&mutex_stats_lock);
diff --git a/modules/spl/spl-proc.c b/modules/spl/spl-proc.c
index a8d3485a6..4a7dcec96 100644
--- a/modules/spl/spl-proc.c
+++ b/modules/spl/spl-proc.c
@@ -325,6 +325,7 @@ proc_console_backoff(struct ctl_table *table, int write, struct file *filp,
         RETURN(rc);
 }
 
+#ifdef DEBUG_KMEM
 static int
 proc_doatomic64(struct ctl_table *table, int write, struct file *filp,
                 void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -349,6 +350,7 @@ proc_doatomic64(struct ctl_table *table, int write, struct file *filp,
 
         RETURN(rc);
 }
+#endif /* DEBUG_KMEM */
 
 static int
 proc_dohostid(struct ctl_table *table, int write, struct file *filp,
@@ -829,7 +831,9 @@ proc_init(void)
 
 	RETURN(rc);
 out2:
+#ifdef DEBUG_MUTEX
         remove_proc_entry("stats_per", proc_sys_spl_mutex);
+#endif /* DEBUG_MUTEX */
 out:
         unregister_sysctl_table(spl_header);
 #endif /* CONFIG_SYSCTL */
@@ -843,7 +847,9 @@ proc_fini(void)
 
 #ifdef CONFIG_SYSCTL
         ASSERT(spl_header != NULL);
+#ifdef DEBUG_MUTEX
         remove_proc_entry("stats_per", proc_sys_spl_mutex);
+#endif /* DEBUG_MUTEX */
         unregister_sysctl_table(spl_header);
 #endif
         EXIT;