diff --git a/c_src/async_nif.h b/c_src/async_nif.h
index 6627152..13bbce7 100644
--- a/c_src/async_nif.h
+++ b/c_src/async_nif.h
@@ -320,6 +320,7 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
       if (!fifo_q_full(reqs, q->reqs)) {
           await = __stat_mean_log2(async_nif->qwait_stat);
           await_inthisq = __stat_mean_log2(q->qwait_stat);
+	  //DPRINTF("q:%d %f/%f", qid, await_inthisq, await);
           if (await_inthisq > await) {
               enif_mutex_unlock(q->reqs_mutex);
               qid = (qid + 1) % async_nif->num_queues;
diff --git a/c_src/stats.c b/c_src/stats.c
index 9d56f9e..7b9c28f 100644
--- a/c_src/stats.c
+++ b/c_src/stats.c
@@ -99,40 +99,27 @@ __stat_mean_log2(struct stat *s)
 uint64_t
 __stat_tick(struct stat *s)
 {
-    duration_t *d;
     uint64_t t;
 
     if (!s)
 	return 0.0;
 
-    d = (duration_t*)erl_drv_tsd_get(s->duration_key);
-    if (!d) {
-	if ((d = enif_alloc(sizeof(duration_t))) == NULL)
-	    return 0;
-	memset(d, 0, sizeof(duration_t));
-	erl_drv_tsd_set(s->duration_key, d);
-    }
-    t = ts(d->unit);
-    d->then = t;
+    t = ts(s->d.unit);
+    s->d.then = t;
     return t;
 }
 
 void
 __stat_reset(struct stat *s)
 {
-    duration_t *d;
-
     if (!s)
 	return;
 
-    s->min = ~0;
-    s->max = 0;
     s->h = 0;
+    s->d.unit = ns;
+    s->d.then = 0;
     memset(s->histogram, 0, sizeof(uint64_t) * 64);
     memset(s->samples, 0, sizeof(uint64_t) * s->num_samples);
-    d = (duration_t*)erl_drv_tsd_get(s->duration_key);
-    if (d)
-	d->then = 0;
 }
 
 uint64_t
@@ -146,10 +133,7 @@ __stat_tock(struct stat *s)
     if (!s)
 	return 0.0;
 
-    d = (duration_t*)erl_drv_tsd_get(s->duration_key);
-    if (!d)
-	return 0;
-
+    d = &s->d;
     now = ts(d->unit);
     elapsed = now - d->then;
     i = s->h;
@@ -160,7 +144,7 @@ __stat_tock(struct stat *s)
     }
     s->h = (s->h + 1) % s->num_samples;
     s->samples[i] = elapsed;
-    if (elapsed < s->min)
+    if (elapsed != 0 && elapsed < s->min)
 	s->min = elapsed;
     if (elapsed > s->max)
 	s->max = elapsed;
@@ -255,6 +239,6 @@ __stat_init(uint32_t n)
     s->mean = 0.0;
     s->h = 0;
     s->num_samples = n;
-    erl_drv_tsd_key_create(NULL, &(s->duration_key));
+    s->d.unit = ns;
     return s;
 }
diff --git a/c_src/stats.h b/c_src/stats.h
index 6d7f983..0bdbe8e 100644
--- a/c_src/stats.h
+++ b/c_src/stats.h
@@ -30,7 +30,7 @@ extern "C" {
 #define STAT_DEF(name) struct stat *name ## _stat;
 
 struct stat {
-    ErlDrvTSDKey duration_key;
+    duration_t d;
     uint32_t h, n, num_samples;
     uint64_t min, max;
     double mean;
diff --git a/c_src/wterl.c b/c_src/wterl.c
index 5f44ae7..95c4cf4 100644
--- a/c_src/wterl.c
+++ b/c_src/wterl.c
@@ -193,12 +193,11 @@ static inline uint32_t __log2(uint64_t x) {
 static int
 __ctx_cache_evict(WterlConnHandle *conn_handle)
 {
-    static uint16_t ncalls = 0;
     uint32_t mean, log, num_evicted, i;
     uint64_t now, elapsed;
     struct wterl_ctx *c, *n;
 
-    if (conn_handle->cache_size < MAX_CACHE_SIZE && ++ncalls != 0)
+    if (conn_handle->cache_size < MAX_CACHE_SIZE)
         return 0;
 
     now = cpu_clock_ticks();
@@ -264,7 +263,15 @@ __ctx_cache_find(WterlConnHandle *conn_handle, const uint64_t sig)
         }
         c = STAILQ_NEXT(c, entries);
     }
+#ifdef DEBUG
+    uint32_t sz = 0;
+    struct wterl_ctx *f;
+    STAILQ_FOREACH(f, &conn_handle->cache, entries) {
+	sz++;
+    }
+#endif
     enif_mutex_unlock(conn_handle->cache_mutex);
+    DPRINTF("cache_find: [%u:%u] %s (%p)", sz, conn_handle->cache_size, c ? "hit" : "miss", c);
     return c;
 }
 
@@ -282,7 +289,15 @@ __ctx_cache_add(WterlConnHandle *conn_handle, struct wterl_ctx *c)
     c->tstamp = cpu_clock_ticks();
     STAILQ_INSERT_TAIL(&conn_handle->cache, c, entries);
     conn_handle->cache_size += 1;
+#ifdef DEBUG
+    uint32_t sz = 0;
+    struct wterl_ctx *f;
+    STAILQ_FOREACH(f, &conn_handle->cache, entries) {
+	sz++;
+    }
+#endif
     enif_mutex_unlock(conn_handle->cache_mutex);
+    DPRINTF("cache_add: [%u:%u] (%p)", sz, conn_handle->cache_size, c);
 }
 
 static inline char *
diff --git a/src/wterl.erl b/src/wterl.erl
index 495be92..db44807 100644
--- a/src/wterl.erl
+++ b/src/wterl.erl
@@ -604,7 +604,7 @@ insert_delete_test() ->
 %%		 lists:sort([crypto:sha(<<X>>) || X <- lists:seq(1, 2000)])).
 
 many_open_tables_test_() ->
-    {timeout, 60,
+    {timeout, 120,
      fun() ->
 	     ConnOpts = [{create,true},{cache_size,"100MB"},{session_max, 8192}],
 	     DataDir = ?TEST_DATA_DIR,