diff --git a/script/shell_stat.sh b/script/shell_stat.sh
index 9590850..0ba64a3 100644
--- a/script/shell_stat.sh
+++ b/script/shell_stat.sh
@@ -60,7 +60,7 @@ calculate() {
     local fields=($(echo "$curr_data" | jq -r '.[].fields | to_entries | .[] | .key' | grep -v timestamp_ms))
     local curr_ts=$(echo "$curr_data" | jq -r '.[].timestamp_ms')
     local prev_ts=$(echo "$prev_data" | jq -r '.[].timestamp_ms')
-    local diff_ts=$((($curr_ts - $prev_ts) / 1000))
+    local diff_ts=$(($curr_ts - $prev_ts))
     local seconds=$((curr_ts / 1000))
     local buffer=()
 
@@ -78,7 +78,7 @@ calculate() {
         if [ $diff_ts -eq 0 ]; then
             speed=0
         else
-            speed=$((diff_val / diff_ts))
+            speed=$((diff_val * 1000 / diff_ts))
         fi
         buffer+=("$(printf "%-30s" $field)$(printf "%-20s" $curr_val)$(printf "%-20s" $speed)\n")
     done
diff --git a/src/stellar/stellar.cpp b/src/stellar/stellar.cpp
index 5e9c04b..92481de 100644
--- a/src/stellar/stellar.cpp
+++ b/src/stellar/stellar.cpp
@@ -29,7 +29,6 @@ struct stellar_thread
     pthread_t tid;
     uint16_t idx;
     uint64_t is_runing;
-    uint64_t stat_last_merge_ts;
     uint64_t timing_wheel_last_update_ts;
     struct ip_reassembly *ip_mgr;
     struct session_manager *sess_mgr;
@@ -257,12 +256,7 @@ static void *work_thread(void *arg)
             thread->timing_wheel_last_update_ts = now;
         }
 
-        if (now - thread->stat_last_merge_ts > 1000)
-        {
-            merge_thread_stat(thread, now);
-            thread->stat_last_merge_ts = now;
-        }
-
+        merge_thread_stat(thread, now);
         ip_reassembly_expire(ip_reass, now);
 
         // TODO
@@ -289,7 +283,6 @@ static int stellar_thread_init(struct stellar_runtime *ctx, uint8_t nr_threads)
         struct stellar_thread *thread = &ctx->threads[i];
         thread->idx = i;
         thread->is_runing = 0;
-        thread->stat_last_merge_ts = now;
         thread->timing_wheel_last_update_ts = now;
         thread->sess_mgr = session_manager_new(&config->sess_mgr_opts, now);
         if (thread->sess_mgr == NULL)
@@ -419,7 +412,7 @@ int main(int argc, char **argv)
     while (!ATOMIC_READ(&runtime->need_exit))
     {
         timestamp_update();
-        if (timestamp_get_msec() - runtime->stat_last_output_ts > 1000)
+        if (timestamp_get_msec() - runtime->stat_last_output_ts > 2000)
         {
             runtime->stat_last_output_ts = timestamp_get_msec();
             stellar_stat_output(runtime->stat);