diff --git a/src/meta/meta_data.cpp b/src/meta/meta_data.cpp
index 46cd8ac5cd..33af192627 100644
--- a/src/meta/meta_data.cpp
+++ b/src/meta/meta_data.cpp
@@ -235,7 +235,7 @@ void proposal_actions::track_current_learner(const dsn::rpc_address &node, const
                 current_learner.last_committed_decree > info.last_committed_decree ||
                 current_learner.last_prepared_decree > info.last_prepared_decree) {
 
-                // TODO: need to add a perf counter here
+                // TODO: need to add a metric here.
                 LOG_WARNING("{}: learner({})'s progress step back, please trace this carefully",
                             info.pid,
                             node);
diff --git a/src/replica/bulk_load/replica_bulk_loader.h b/src/replica/bulk_load/replica_bulk_loader.h
index 5559f6d4a0..92f76810cd 100644
--- a/src/replica/bulk_load/replica_bulk_loader.h
+++ b/src/replica/bulk_load/replica_bulk_loader.h
@@ -194,7 +194,8 @@ class replica_bulk_loader : replica_base
     std::map<std::string, task_ptr> _download_files_task;
     // download metadata and create download file tasks
     task_ptr _download_task;
-    // Used for perf-counter
+
+    // Used for metrics.
     uint64_t _bulk_load_start_time_ms{0};
 
     METRIC_VAR_DECLARE_counter(bulk_load_downloading_count);
diff --git a/src/replica/duplication/mutation_batch.cpp b/src/replica/duplication/mutation_batch.cpp
index 8b7a815fca..e6d91d5f29 100644
--- a/src/replica/duplication/mutation_batch.cpp
+++ b/src/replica/duplication/mutation_batch.cpp
@@ -74,7 +74,7 @@ void mutation_buffer::commit(decree d, commit_type ct)
         //             n+m(m>1)            n+k(k>=m)
         //
         // just LOG_ERROR but not CHECK if mutation loss or other problem, it's different from
-        // base class implement. And from the error and perf-counter, we can choose restart
+        // base class implement. And based on the error and metric, we can choose to restart
         // duplication or ignore the loss.
         if (next_committed_mutation == nullptr || !next_committed_mutation->is_logged()) {
             LOG_ERROR_PREFIX("mutation[{}] is lost in prepare_list: "
diff --git a/src/replica/replica.h b/src/replica/replica.h
index 83e78105aa..8ba5bde32a 100644
--- a/src/replica/replica.h
+++ b/src/replica/replica.h
@@ -641,7 +641,6 @@ class replica : public serverlet<replica>, public ref_counter, public replica_ba
 
     std::unique_ptr<replica_follower> _replica_follower;
 
-    // perf counters
     METRIC_VAR_DECLARE_gauge_int64(private_log_size_mb);
     METRIC_VAR_DECLARE_counter(throttling_delayed_write_requests);
     METRIC_VAR_DECLARE_counter(throttling_rejected_write_requests);
diff --git a/src/replica/replica_context.h b/src/replica/replica_context.h
index 32da41d38b..3b6220fa2a 100644
--- a/src/replica/replica_context.h
+++ b/src/replica/replica_context.h
@@ -285,7 +285,7 @@ class partition_split_context
     // see more in function `child_check_split_context` and `parent_check_states`
     task_ptr check_state_task;
 
-    // Used for split related perf-counter
+    // Used for split-related metrics.
     uint64_t splitting_start_ts_ns{0};
     uint64_t splitting_start_async_learn_ts_ns{0};
     uint64_t splitting_copy_file_count{0};
diff --git a/src/replica/split/replica_split_manager.h b/src/replica/split/replica_split_manager.h
index 7435e1705d..00c6f81ef9 100644
--- a/src/replica/split/replica_split_manager.h
+++ b/src/replica/split/replica_split_manager.h
@@ -94,7 +94,7 @@ class replica_split_manager : replica_base
                             uint64_t total_file_size,
                             decree last_committed_decree);
 
-    // TODO(heyuchen): total_file_size is used for split perf-counter in further pull request
+    // TODO(heyuchen): total_file_size is used for split-related  metrics in further pull request.
     // Applies mutation logs that were learned from the parent of this child.
     // This stage follows after that child applies the checkpoint of parent, and begins to apply the
     // mutations.
diff --git a/src/runtime/profiler.h b/src/runtime/profiler.h
index d283a5b4ae..a4630d226a 100644
--- a/src/runtime/profiler.h
+++ b/src/runtime/profiler.h
@@ -34,8 +34,8 @@
 
 Profiler toollet
 
-This toollet collects many performance counter values for the specified tasks,
-as configed below.
+This toollet collects many performance metrics for the specified tasks,
+as configured below.
 
 <PRE>
 
diff --git a/src/server/pegasus_write_service.h b/src/server/pegasus_write_service.h
index 18db638176..eed596e355 100644
--- a/src/server/pegasus_write_service.h
+++ b/src/server/pegasus_write_service.h
@@ -239,7 +239,7 @@ class pegasus_write_service : dsn::replication::replica_base
     uint32_t _put_batch_size;
     uint32_t _remove_batch_size;
 
-    // TODO(wutao1): add perf counters for failed rpc.
+    // TODO(wutao1): add metrics for failed rpc.
 };
 
 } // namespace server
diff --git a/src/server/test/pegasus_server_impl_test.cpp b/src/server/test/pegasus_server_impl_test.cpp
index 0508e7ce56..a1cf77db4c 100644
--- a/src/server/test/pegasus_server_impl_test.cpp
+++ b/src/server/test/pegasus_server_impl_test.cpp
@@ -53,13 +53,13 @@ class pegasus_server_impl_test : public pegasus_server_test_base
 
     void test_table_level_slow_query()
     {
-        // the on_get function will sleep 10ms for unit test,
-        // so when we set slow_query_threshold <= 10ms, the perf counter will be incr by 1
+        // The function `on_get` will sleep 10ms for the unit test. Thus when we set
+        // slow_query_threshold <= 10ms, the metric `abnormal_read_requests` will increment by 1.
         struct test_case
         {
             bool is_multi_get; // false-on_get, true-on_multi_get
             uint64_t slow_query_threshold_ms;
-            uint8_t expect_perf_counter_incr;
+            uint8_t expected_incr;
         } tests[] = {{false, 10, 1}, {false, 300, 0}, {true, 10, 1}, {true, 300, 0}};
 
         // test key
@@ -93,7 +93,7 @@ class pegasus_server_impl_test : public pegasus_server_test_base
             }
             auto after_count = _server->METRIC_VAR_VALUE(abnormal_read_requests);
 
-            ASSERT_EQ(before_count + test.expect_perf_counter_incr, after_count);
+            ASSERT_EQ(before_count + test.expected_incr, after_count);
         }
     }
 
diff --git a/src/utils/api_utilities.h b/src/utils/api_utilities.h
index 537ceaaedd..ec0733ae5c 100644
--- a/src/utils/api_utilities.h
+++ b/src/utils/api_utilities.h
@@ -24,10 +24,7 @@
  * THE SOFTWARE.
  */
 
-// some useful utility functions provided by rDSN,
-// such as logging, performance counter, checksum,
-// command line interface registration and invocation,
-// etc.
+// Some useful utility functions for logging and mocking provided by rDSN.
 
 #pragma once