diff --git a/include/jemalloc/internal/jemalloc_internal_types.h b/include/jemalloc/internal/jemalloc_internal_types.h
index 6a81f3cd..cddbfb65 100644
--- a/include/jemalloc/internal/jemalloc_internal_types.h
+++ b/include/jemalloc/internal/jemalloc_internal_types.h
@@ -145,4 +145,6 @@ typedef enum malloc_init_e malloc_init_t;
 	assert(sizeof(type) * (count) <= VARIABLE_ARRAY_SIZE_MAX);	\
 	VARIABLE_ARRAY_UNSAFE(type, name, count)
 
+#define CALLOC_MADVISE_THRESHOLD_DEFAULT (((size_t)1) << 23) /* 8 MB */
+
 #endif /* JEMALLOC_INTERNAL_TYPES_H */
diff --git a/src/jemalloc.c b/src/jemalloc.c
index a4509e68..c6621a79 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -158,7 +158,7 @@ void (*JET_MUTABLE invalid_conf_abort)(void) = &abort;
 bool	opt_utrace = false;
 bool	opt_xmalloc = false;
 bool	opt_experimental_infallible_new = false;
-bool	opt_experimental_tcache_gc = false;
+bool	opt_experimental_tcache_gc = true;
 bool	opt_zero = false;
 unsigned	opt_narenas = 0;
 static fxp_t		opt_narenas_ratio = FXP_INIT_INT(4);
@@ -168,7 +168,8 @@ unsigned	ncpus;
 unsigned opt_debug_double_free_max_scan =
     SAFETY_CHECK_DOUBLE_FREE_MAX_SCAN_DEFAULT;
 
-size_t opt_calloc_madvise_threshold = 0;
+size_t opt_calloc_madvise_threshold =
+    CALLOC_MADVISE_THRESHOLD_DEFAULT;
 
 /* Protects arenas initialization. */
 static malloc_mutex_t arenas_lock;