diff --git a/include/jemalloc/internal/rtree_externs.h b/include/jemalloc/internal/rtree_externs.h
index 842eb0b5..5145c12c 100644
--- a/include/jemalloc/internal/rtree_externs.h
+++ b/include/jemalloc/internal/rtree_externs.h
@@ -23,7 +23,7 @@ static const rtree_level_t rtree_levels[] = {
 #endif
 };
 
-bool rtree_new(rtree_t *rtree);
+bool rtree_new(rtree_t *rtree, bool zeroed);
 #ifdef JEMALLOC_JET
 typedef rtree_node_elm_t *(rtree_node_alloc_t)(tsdn_t *, rtree_t *, size_t);
 extern rtree_node_alloc_t *rtree_node_alloc;
diff --git a/include/jemalloc/internal/rtree_structs.h b/include/jemalloc/internal/rtree_structs.h
index e9a507ab..3ecdf810 100644
--- a/include/jemalloc/internal/rtree_structs.h
+++ b/include/jemalloc/internal/rtree_structs.h
@@ -39,13 +39,17 @@ struct rtree_ctx_s {
 #ifndef _MSC_VER
 	JEMALLOC_ALIGNED(CACHELINE)
 #endif
-	rtree_ctx_cache_elm_t cache[RTREE_CTX_NCACHE];
+	rtree_ctx_cache_elm_t	cache[RTREE_CTX_NCACHE];
 };
 
 struct rtree_s {
-	/* An rtree_{internal,leaf}_elm_t *. */
-	atomic_p_t	root;
-	malloc_mutex_t	init_lock;
+	malloc_mutex_t		init_lock;
+	/* Number of elements based on rtree_levels[0].bits. */
+#if RTREE_HEIGHT > 1
+	rtree_node_elm_t	root[1U << (RTREE_NSB/RTREE_HEIGHT)];
+#else
+	rtree_leaf_elm_t	root[1U << (RTREE_NSB/RTREE_HEIGHT)];
+#endif
 };
 
 #endif /* JEMALLOC_INTERNAL_RTREE_STRUCTS_H */
diff --git a/src/extent.c b/src/extent.c
index a95e2748..f1b513e4 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -1658,7 +1658,7 @@ extent_merge_wrapper(tsdn_t *tsdn, arena_t *arena,
 
 bool
 extent_boot(void) {
-	if (rtree_new(&extents_rtree)) {
+	if (rtree_new(&extents_rtree, true)) {
 		return true;
 	}
 
diff --git a/src/rtree.c b/src/rtree.c
index 18197390..a07380f3 100644
--- a/src/rtree.c
+++ b/src/rtree.c
@@ -6,8 +6,15 @@
  * used.
  */
 bool
-rtree_new(rtree_t *rtree) {
-	atomic_store_p(&rtree->root, NULL, ATOMIC_RELAXED);
+rtree_new(rtree_t *rtree, bool zeroed) {
+#ifdef JEMALLOC_JET
+	if (!zeroed) {
+		memset(rtree, 0, sizeof(rtree_t)); /* Clear root. */
+	}
+#else
+	assert(zeroed);
+#endif
+
 	if (malloc_mutex_init(&rtree->init_lock, "rtree", WITNESS_RANK_RTREE)) {
 		return true;
 	}
@@ -76,6 +83,7 @@ rtree_leaf_dalloc_t *rtree_leaf_dalloc = JEMALLOC_N(rtree_leaf_dalloc_impl);
 #endif
 
 #ifdef JEMALLOC_JET
+#  if RTREE_HEIGHT > 1
 static void
 rtree_delete_subtree(tsdn_t *tsdn, rtree_t *rtree, rtree_node_elm_t *subtree,
     unsigned level) {
@@ -101,25 +109,17 @@ rtree_delete_subtree(tsdn_t *tsdn, rtree_t *rtree, rtree_node_elm_t *subtree,
 		}
 	}
 
-	rtree_node_dalloc(tsdn, rtree, subtree);
+	if (subtree != rtree->root) {
+		rtree_node_dalloc(tsdn, rtree, subtree);
+	}
 }
+#  endif
 
 void
 rtree_delete(tsdn_t *tsdn, rtree_t *rtree) {
-	if (RTREE_HEIGHT > 1) {
-		rtree_node_elm_t *node = (rtree_node_elm_t *)atomic_load_p(
-		    &rtree->root, ATOMIC_RELAXED);
-		if (node != NULL) {
-			rtree_delete_subtree(tsdn, rtree, node, 0);
-		}
-	} else {
-		rtree_leaf_elm_t *leaf =
-		    (rtree_leaf_elm_t *)atomic_load_p(&rtree->root,
-		    ATOMIC_RELAXED);
-		if (leaf != NULL) {
-			rtree_leaf_dalloc(tsdn, rtree, leaf);
-		}
-	}
+#  if RTREE_HEIGHT > 1
+	rtree_delete_subtree(tsdn, rtree, rtree->root, 0);
+#  endif
 }
 #endif
 
@@ -244,70 +244,21 @@ rtree_child_leaf_read(tsdn_t *tsdn, rtree_t *rtree, rtree_node_elm_t *elm,
 	return leaf;
 }
 
-UNUSED static rtree_node_elm_t *
-rtree_root_node_tryread(rtree_t *rtree, bool dependent) {
-	rtree_node_elm_t *node;
-	if (dependent) {
-		node = (rtree_node_elm_t *)atomic_load_p(&rtree->root,
-		    ATOMIC_RELAXED);
-	} else {
-		node = (rtree_node_elm_t *)atomic_load_p(&rtree->root,
-		    ATOMIC_ACQUIRE);
-	}
-	assert(!dependent || node != NULL);
-	return node;
-}
-
-UNUSED static rtree_node_elm_t *
-rtree_root_node_read(tsdn_t *tsdn, rtree_t *rtree, bool dependent) {
-	rtree_node_elm_t *node = rtree_root_node_tryread(rtree, dependent);
-	if (!dependent && unlikely(!rtree_node_valid(node))) {
-		node = rtree_node_init(tsdn, rtree, 0, &rtree->root);
-	}
-	assert(!dependent || node != NULL);
-	return node;
-}
-
-UNUSED static rtree_leaf_elm_t *
-rtree_root_leaf_tryread(rtree_t *rtree, bool dependent) {
-	rtree_leaf_elm_t *leaf;
-	if (dependent) {
-		leaf = (rtree_leaf_elm_t *)atomic_load_p(&rtree->root,
-		    ATOMIC_RELAXED);
-	} else {
-		leaf = (rtree_leaf_elm_t *)atomic_load_p(&rtree->root,
-		    ATOMIC_ACQUIRE);
-	}
-	assert(!dependent || leaf != NULL);
-	return leaf;
-}
-
-UNUSED static rtree_leaf_elm_t *
-rtree_root_leaf_read(tsdn_t *tsdn, rtree_t *rtree, bool dependent) {
-	rtree_leaf_elm_t *leaf = rtree_root_leaf_tryread(rtree, dependent);
-	if (!dependent && unlikely(!rtree_leaf_valid(leaf))) {
-		leaf = rtree_leaf_init(tsdn, rtree, &rtree->root);
-	}
-	assert(!dependent || leaf != NULL);
-	return leaf;
-}
-
 rtree_leaf_elm_t *
 rtree_leaf_elm_lookup_hard(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
     uintptr_t key, bool dependent, bool init_missing) {
 	rtree_node_elm_t *node;
 	rtree_leaf_elm_t *leaf;
 #if RTREE_HEIGHT > 1
-	node = init_missing ? rtree_root_node_read(tsdn, rtree, dependent) :
-	    rtree_root_node_tryread(rtree, dependent);
+	node = rtree->root;
 #else
-	leaf = init_missing ? rtree_root_leaf_read(tsdn, rtree, dependent) :
-	    rtree_root_leaf_tryread(rtree, dependent);
+	leaf = rtree->root;
 #endif
 
 #define RTREE_GET_CHILD(level) {					\
 		assert(level < RTREE_HEIGHT-1);				\
-		if (!dependent && unlikely(!rtree_node_valid(node))) {	\
+		if (level != 0 && !dependent &&				\
+		    unlikely(!rtree_node_valid(node))) {		\
 			return NULL;					\
 		}							\
 		uintptr_t subkey = rtree_subkey(key, level);		\
diff --git a/test/unit/rtree.c b/test/unit/rtree.c
index b04e321b..7a25c47d 100644
--- a/test/unit/rtree.c
+++ b/test/unit/rtree.c
@@ -5,13 +5,14 @@ rtree_node_dalloc_t *rtree_node_dalloc_orig;
 rtree_leaf_alloc_t *rtree_leaf_alloc_orig;
 rtree_leaf_dalloc_t *rtree_leaf_dalloc_orig;
 
-rtree_t *test_rtree;
+/* Potentially too large to safely place on the stack. */
+rtree_t test_rtree;
 
 static rtree_node_elm_t *
 rtree_node_alloc_intercept(tsdn_t *tsdn, rtree_t *rtree, size_t nelms) {
 	rtree_node_elm_t *node;
 
-	if (rtree != test_rtree) {
+	if (rtree != &test_rtree) {
 		return rtree_node_alloc_orig(tsdn, rtree, nelms);
 	}
 
@@ -26,7 +27,7 @@ rtree_node_alloc_intercept(tsdn_t *tsdn, rtree_t *rtree, size_t nelms) {
 static void
 rtree_node_dalloc_intercept(tsdn_t *tsdn, rtree_t *rtree,
     rtree_node_elm_t *node) {
-	if (rtree != test_rtree) {
+	if (rtree != &test_rtree) {
 		rtree_node_dalloc_orig(tsdn, rtree, node);
 		return;
 	}
@@ -38,7 +39,7 @@ static rtree_leaf_elm_t *
 rtree_leaf_alloc_intercept(tsdn_t *tsdn, rtree_t *rtree, size_t nelms) {
 	rtree_leaf_elm_t *leaf;
 
-	if (rtree != test_rtree) {
+	if (rtree != &test_rtree) {
 		return rtree_leaf_alloc_orig(tsdn, rtree, nelms);
 	}
 
@@ -53,7 +54,7 @@ rtree_leaf_alloc_intercept(tsdn_t *tsdn, rtree_t *rtree, size_t nelms) {
 static void
 rtree_leaf_dalloc_intercept(tsdn_t *tsdn, rtree_t *rtree,
     rtree_leaf_elm_t *leaf) {
-	if (rtree != test_rtree) {
+	if (rtree != &test_rtree) {
 		rtree_leaf_dalloc_orig(tsdn, rtree, leaf);
 		return;
 	}
@@ -66,14 +67,12 @@ TEST_BEGIN(test_rtree_read_empty) {
 
 	tsdn = tsdn_fetch();
 
-	rtree_t rtree;
+	rtree_t *rtree = &test_rtree;
 	rtree_ctx_t rtree_ctx = RTREE_CTX_INITIALIZER;
-	test_rtree = &rtree;
-	assert_false(rtree_new(&rtree), "Unexpected rtree_new() failure");
-	assert_ptr_null(rtree_extent_read(tsdn, &rtree, &rtree_ctx, PAGE,
+	assert_false(rtree_new(rtree, false), "Unexpected rtree_new() failure");
+	assert_ptr_null(rtree_extent_read(tsdn, rtree, &rtree_ctx, PAGE,
 	    false), "rtree_extent_read() should return NULL for empty tree");
-	rtree_delete(tsdn, &rtree);
-	test_rtree = NULL;
+	rtree_delete(tsdn, rtree);
 }
 TEST_END
 
@@ -83,7 +82,7 @@ TEST_END
 #define SEED		42
 
 typedef struct {
-	rtree_t		rtree;
+	rtree_t		*rtree;
 	uint32_t	seed;
 } thd_start_arg_t;
 
@@ -108,26 +107,26 @@ thd_start(void *varg) {
 		    MAX_NBITS) - ZU(1)));
 		if (i % 2 == 0) {
 			rtree_leaf_elm_t *elm = rtree_leaf_elm_acquire(tsdn,
-			    &arg->rtree, &rtree_ctx, key, false, true);
+			    arg->rtree, &rtree_ctx, key, false, true);
 			assert_ptr_not_null(elm,
 			    "Unexpected rtree_leaf_elm_acquire() failure");
-			rtree_leaf_elm_write(tsdn, &arg->rtree, elm, true,
+			rtree_leaf_elm_write(tsdn, arg->rtree, elm, true,
 			    extent, NSIZES, false);
-			rtree_leaf_elm_release(tsdn, &arg->rtree, elm);
+			rtree_leaf_elm_release(tsdn, arg->rtree, elm);
 
-			elm = rtree_leaf_elm_acquire(tsdn, &arg->rtree,
+			elm = rtree_leaf_elm_acquire(tsdn, arg->rtree,
 			    &rtree_ctx, key, true, false);
 			assert_ptr_not_null(elm,
 			    "Unexpected rtree_leaf_elm_acquire() failure");
-			rtree_leaf_elm_extent_read(tsdn, &arg->rtree, elm, true,
+			rtree_leaf_elm_extent_read(tsdn, arg->rtree, elm, true,
 			    true);
-			rtree_leaf_elm_szind_read(tsdn, &arg->rtree, elm, true,
+			rtree_leaf_elm_szind_read(tsdn, arg->rtree, elm, true,
 			    true);
-			rtree_leaf_elm_slab_read(tsdn, &arg->rtree, elm, true,
+			rtree_leaf_elm_slab_read(tsdn, arg->rtree, elm, true,
 			    true);
-			rtree_leaf_elm_release(tsdn, &arg->rtree, elm);
+			rtree_leaf_elm_release(tsdn, arg->rtree, elm);
 		} else {
-			rtree_extent_read(tsdn, &arg->rtree, &rtree_ctx, key,
+			rtree_extent_read(tsdn, arg->rtree, &rtree_ctx, key,
 			    false);
 		}
 	}
@@ -145,8 +144,9 @@ TEST_BEGIN(test_rtree_concurrent) {
 
 	sfmt = init_gen_rand(SEED);
 	tsdn = tsdn_fetch();
-	test_rtree = &arg.rtree;
-	assert_false(rtree_new(&arg.rtree), "Unexpected rtree_new() failure");
+	arg.rtree = &test_rtree;
+	assert_false(rtree_new(arg.rtree, false),
+	    "Unexpected rtree_new() failure");
 	arg.seed = gen_rand32(sfmt);
 	for (unsigned i = 0; i < NTHREADS; i++) {
 		thd_create(&thds[i], thd_start, (void *)&arg);
@@ -154,8 +154,7 @@ TEST_BEGIN(test_rtree_concurrent) {
 	for (unsigned i = 0; i < NTHREADS; i++) {
 		thd_join(thds[i], NULL);
 	}
-	rtree_delete(tsdn, &arg.rtree);
-	test_rtree = NULL;
+	rtree_delete(tsdn, arg.rtree);
 	fini_gen_rand(sfmt);
 }
 TEST_END
@@ -173,29 +172,27 @@ TEST_BEGIN(test_rtree_extrema) {
 
 	tsdn_t *tsdn = tsdn_fetch();
 
-	rtree_t rtree;
+	rtree_t *rtree = &test_rtree;
 	rtree_ctx_t rtree_ctx = RTREE_CTX_INITIALIZER;
-	test_rtree = &rtree;
-	assert_false(rtree_new(&rtree), "Unexpected rtree_new() failure");
+	assert_false(rtree_new(rtree, false), "Unexpected rtree_new() failure");
 
-	assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, PAGE, &extent_a,
+	assert_false(rtree_write(tsdn, rtree, &rtree_ctx, PAGE, &extent_a,
 	    extent_szind_get(&extent_a), extent_slab_get(&extent_a)),
 	    "Unexpected rtree_write() failure");
-	rtree_szind_slab_update(tsdn, &rtree, &rtree_ctx, PAGE,
+	rtree_szind_slab_update(tsdn, rtree, &rtree_ctx, PAGE,
 	    extent_szind_get(&extent_a), extent_slab_get(&extent_a));
-	assert_ptr_eq(rtree_extent_read(tsdn, &rtree, &rtree_ctx, PAGE, true),
+	assert_ptr_eq(rtree_extent_read(tsdn, rtree, &rtree_ctx, PAGE, true),
 	    &extent_a,
 	    "rtree_extent_read() should return previously set value");
 
-	assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, ~((uintptr_t)0),
+	assert_false(rtree_write(tsdn, rtree, &rtree_ctx, ~((uintptr_t)0),
 	    &extent_b, extent_szind_get_maybe_invalid(&extent_b),
 	    extent_slab_get(&extent_b)), "Unexpected rtree_write() failure");
-	assert_ptr_eq(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+	assert_ptr_eq(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 	    ~((uintptr_t)0), true), &extent_b,
 	    "rtree_extent_read() should return previously set value");
 
-	rtree_delete(tsdn, &rtree);
-	test_rtree = NULL;
+	rtree_delete(tsdn, rtree);
 }
 TEST_END
 
@@ -209,33 +206,30 @@ TEST_BEGIN(test_rtree_bits) {
 	extent_init(&extent, NULL, NULL, 0, false, NSIZES, 0,
 	    extent_state_active, false, false);
 
-	rtree_t rtree;
+	rtree_t *rtree = &test_rtree;
 	rtree_ctx_t rtree_ctx = RTREE_CTX_INITIALIZER;
 
-	test_rtree = &rtree;
-	assert_false(rtree_new(&rtree),
-	    "Unexpected rtree_new() failure");
+	assert_false(rtree_new(rtree, false), "Unexpected rtree_new() failure");
 
 	for (unsigned i = 0; i < sizeof(keys)/sizeof(uintptr_t); i++) {
-		assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, keys[i],
+		assert_false(rtree_write(tsdn, rtree, &rtree_ctx, keys[i],
 		    &extent, NSIZES, false),
 		    "Unexpected rtree_write() failure");
 		for (unsigned j = 0; j < sizeof(keys)/sizeof(uintptr_t); j++) {
-			assert_ptr_eq(rtree_extent_read(tsdn, &rtree,
-			    &rtree_ctx, keys[j], true),
-			    &extent, "rtree_extent_read() should return "
-			    "previously set value and ignore insignificant key "
-			    "bits; i=%u, j=%u, set key=%#"FMTxPTR", get "
-			    "key=%#"FMTxPTR, i, j, keys[i], keys[j]);
+			assert_ptr_eq(rtree_extent_read(tsdn, rtree, &rtree_ctx,
+			    keys[j], true), &extent,
+			    "rtree_extent_read() should return previously set "
+			    "value and ignore insignificant key bits; i=%u, "
+			    "j=%u, set key=%#"FMTxPTR", get key=%#"FMTxPTR, i,
+			    j, keys[i], keys[j]);
 		}
-		assert_ptr_null(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+		assert_ptr_null(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 		    (((uintptr_t)2) << LG_PAGE), false),
 		    "Only leftmost rtree leaf should be set; i=%u", i);
-		rtree_clear(tsdn, &rtree, &rtree_ctx, keys[i]);
+		rtree_clear(tsdn, rtree, &rtree_ctx, keys[i]);
 	}
 
-	rtree_delete(tsdn, &rtree);
-	test_rtree = NULL;
+	rtree_delete(tsdn, rtree);
 }
 TEST_END
 
@@ -245,50 +239,48 @@ TEST_BEGIN(test_rtree_random) {
 	sfmt_t *sfmt = init_gen_rand(SEED);
 	tsdn_t *tsdn = tsdn_fetch();
 	uintptr_t keys[NSET];
-	rtree_t rtree;
+	rtree_t *rtree = &test_rtree;
 	rtree_ctx_t rtree_ctx = RTREE_CTX_INITIALIZER;
 
 	extent_t extent;
 	extent_init(&extent, NULL, NULL, 0, false, NSIZES, 0,
 	    extent_state_active, false, false);
 
-	test_rtree = &rtree;
-	assert_false(rtree_new(&rtree), "Unexpected rtree_new() failure");
+	assert_false(rtree_new(rtree, false), "Unexpected rtree_new() failure");
 
 	for (unsigned i = 0; i < NSET; i++) {
 		keys[i] = (uintptr_t)gen_rand64(sfmt);
-		rtree_leaf_elm_t *elm = rtree_leaf_elm_acquire(tsdn, &rtree,
+		rtree_leaf_elm_t *elm = rtree_leaf_elm_acquire(tsdn, rtree,
 		    &rtree_ctx, keys[i], false, true);
 		assert_ptr_not_null(elm,
 		    "Unexpected rtree_leaf_elm_acquire() failure");
-		rtree_leaf_elm_write(tsdn, &rtree, elm, true, &extent, NSIZES,
+		rtree_leaf_elm_write(tsdn, rtree, elm, true, &extent, NSIZES,
 		    false);
-		rtree_leaf_elm_release(tsdn, &rtree, elm);
-		assert_ptr_eq(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+		rtree_leaf_elm_release(tsdn, rtree, elm);
+		assert_ptr_eq(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 		    keys[i], true), &extent,
 		    "rtree_extent_read() should return previously set value");
 	}
 	for (unsigned i = 0; i < NSET; i++) {
-		assert_ptr_eq(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+		assert_ptr_eq(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 		    keys[i], true), &extent,
 		    "rtree_extent_read() should return previously set value, "
 		    "i=%u", i);
 	}
 
 	for (unsigned i = 0; i < NSET; i++) {
-		rtree_clear(tsdn, &rtree, &rtree_ctx, keys[i]);
-		assert_ptr_null(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+		rtree_clear(tsdn, rtree, &rtree_ctx, keys[i]);
+		assert_ptr_null(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 		    keys[i], true),
 		   "rtree_extent_read() should return previously set value");
 	}
 	for (unsigned i = 0; i < NSET; i++) {
-		assert_ptr_null(rtree_extent_read(tsdn, &rtree, &rtree_ctx,
+		assert_ptr_null(rtree_extent_read(tsdn, rtree, &rtree_ctx,
 		    keys[i], true),
 		    "rtree_extent_read() should return previously set value");
 	}
 
-	rtree_delete(tsdn, &rtree);
-	test_rtree = NULL;
+	rtree_delete(tsdn, rtree);
 	fini_gen_rand(sfmt);
 #undef NSET
 #undef SEED
@@ -305,7 +297,6 @@ main(void) {
 	rtree_leaf_alloc = rtree_leaf_alloc_intercept;
 	rtree_leaf_dalloc_orig = rtree_leaf_dalloc;
 	rtree_leaf_dalloc = rtree_leaf_dalloc_intercept;
-	test_rtree = NULL;
 
 	return test(
 	    test_rtree_read_empty,