diff --git a/deltann/Makefile b/deltann/Makefile
index 99569725..b0fedbca 100644
--- a/deltann/Makefile
+++ b/deltann/Makefile
@@ -61,8 +61,8 @@ CC := gcc
 CXX := g++
 AR := ar
 
-CFLAGS := -g -O2
-CXXFLAGS := -O2 -std=c++11 -fPIC -DDELTANN_VERSION=\"$(shell git rev-parse --short HEAD)\" -DNDEBUG
+CFLAGS := -O2
+CXXFLAGS := -O3 -std=c++11 -fPIC -DDELTANN_VERSION=\"$(shell git rev-parse --short HEAD)\" -DNDEBUG
 LDFLAGS := -Wl,--version-script=deltann_version_script.lds
 ARFLAGS := -r
 
diff --git a/deltann/api/c_api.cc b/deltann/api/c_api.cc
index f4a95989..92c40d45 100644
--- a/deltann/api/c_api.cc
+++ b/deltann/api/c_api.cc
@@ -19,7 +19,7 @@ limitations under the License.
 
 #include "api/c_api.h"
 #include "core/runtime.h"
-#include "core/utils/config.h"
+#include "core/config.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/deltann/core/base_model.h b/deltann/core/base_model.h
index 6a0cbb4c..4c0c6d5e 100644
--- a/deltann/core/base_model.h
+++ b/deltann/core/base_model.h
@@ -22,7 +22,7 @@ limitations under the License.
 #include <vector>
 
 #include "core/data.h"
-#include "core/utils/misc.h"
+#include "core/misc.h"
 
 namespace delta {
 namespace core {
diff --git a/deltann/core/buffer.h b/deltann/core/buffer.h
index cfdd48b0..008c2659 100644
--- a/deltann/core/buffer.h
+++ b/deltann/core/buffer.h
@@ -18,8 +18,8 @@ limitations under the License.
 #define DELTANN_CORE_BUFFER_H_
 
 #include <cstdlib>
-#include "core/utils/logging.h"
-#include "core/utils/misc.h"
+#include "core/logging.h"
+#include "core/misc.h"
 
 namespace delta {
 
diff --git a/deltann/core/utils/config.cc b/deltann/core/config.cc
similarity index 98%
rename from deltann/core/utils/config.cc
rename to deltann/core/config.cc
index ffe76b93..52bf4693 100644
--- a/deltann/core/utils/config.cc
+++ b/deltann/core/config.cc
@@ -20,11 +20,11 @@ limitations under the License.
 #include <utility>
 
 #include "core/io.h"
-#include "core/utils/config.h"
+#include "core/config.h"
 
 #include "yaml-cpp/yaml.h"
 
-using namespace ::delta::core;
+// using namespace ::delta::core;
 
 namespace delta {
 
diff --git a/deltann/core/utils/config.h b/deltann/core/config.h
similarity index 95%
rename from deltann/core/utils/config.h
rename to deltann/core/config.h
index dde6a10b..80f1a50c 100644
--- a/deltann/core/utils/config.h
+++ b/deltann/core/config.h
@@ -14,8 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#ifndef DELTANN_UTILS_CONFIG_H_
-#define DELTANN_UTILS_CONFIG_H_
+#ifndef DELTANN_CORE_CONFIG_H_
+#define DELTANN_CORE_CONFIG_H_
 
 #include <iostream>
 #include <string>
@@ -89,4 +89,4 @@ class RuntimeConfig : public Config {
 
 }  // namespace delta
 
-#endif  // DELTANN_UTILS_CONFIG_H_
+#endif  // DELTANN_CORE_CONFIG_H_
diff --git a/deltann/core/data.h b/deltann/core/data.h
index 7fd38157..c6f60248 100644
--- a/deltann/core/data.h
+++ b/deltann/core/data.h
@@ -24,7 +24,7 @@ limitations under the License.
 #include "core/buffer.h"
 #include "core/io.h"
 #include "core/shape.h"
-#include "core/utils/misc.h"
+#include "core/misc.h"
 
 #ifdef USE_TF
 #include "tensorflow/core/framework/tensor_shape.h"
diff --git a/deltann/core/graph.cc b/deltann/core/graph.cc
index b832cd20..bb5a087e 100644
--- a/deltann/core/graph.cc
+++ b/deltann/core/graph.cc
@@ -15,7 +15,7 @@ limitations under the License.
 ==============================================================================*/
 
 #include "core/graph.h"
-#include "core/utils/config.h"
+#include "core/config.h"
 
 namespace delta {
 namespace core {
diff --git a/deltann/core/graph.h b/deltann/core/graph.h
index 07644bd9..16a75939 100644
--- a/deltann/core/graph.h
+++ b/deltann/core/graph.h
@@ -26,7 +26,7 @@ limitations under the License.
 
 #include "core/base_model.h"
 #include "core/io.h"
-#include "core/utils/misc.h"
+#include "core/misc.h"
 
 namespace delta {
 namespace core {
diff --git a/deltann/core/io.h b/deltann/core/io.h
index b96cea28..e826019e 100644
--- a/deltann/core/io.h
+++ b/deltann/core/io.h
@@ -20,7 +20,7 @@ limitations under the License.
 #include <string>
 
 #include "core/shape.h"
-#include "core/utils/misc.h"
+#include "core/misc.h"
 
 #ifdef USE_TF
 #include "tensorflow/core/framework/tensor_shape.h"
diff --git a/deltann/core/utils/logging.h b/deltann/core/logging.h
similarity index 95%
rename from deltann/core/utils/logging.h
rename to deltann/core/logging.h
index 07464a33..5d4ffeb1 100644
--- a/deltann/core/utils/logging.h
+++ b/deltann/core/logging.h
@@ -14,15 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#ifndef DELTANN_UTILS_LOGGING_H_
-#define DELTANN_UTILS_LOGGING_H_
+#ifndef DELTANN_CORE_LOGGING_H_
+#define DELTANN_CORE_LOGGING_H_
 
 #include <cstring>
 #include <ctime>
 #include <sstream>
 #include <string>
 
-#include "core/utils/misc.h"
+#include "core/misc.h"
 
 namespace delta {
 namespace logging {
@@ -100,4 +100,4 @@ class LogMessageFatal : public LogMessage {
 
 }  // namespace delta
 
-#endif  // DELTANN_UTILS_LOGGING_H_
+#endif  // DELTANN_CORE_LOGGING_H_
diff --git a/deltann/core/utils/misc.cc b/deltann/core/misc.cc
similarity index 96%
rename from deltann/core/utils/misc.cc
rename to deltann/core/misc.cc
index f9ffd8d8..936d0878 100644
--- a/deltann/core/utils/misc.cc
+++ b/deltann/core/misc.cc
@@ -18,8 +18,8 @@ limitations under the License.
 #include <cstddef>
 #include <random>
 
-#include "core/utils/logging.h"
-#include "core/utils/misc.h"
+#include "core/logging.h"
+#include "core/misc.h"
 
 namespace delta {
 
@@ -28,7 +28,7 @@ std::size_t delta_sizeof(DataType type) {
     case DataType::DELTA_FLOAT32:
       return sizeof(float);
     case DataType::DELTA_FLOAT16:
-      return sizeof(short);
+      return sizeof(float) / 2;
     case DataType::DELTA_DOUBLE:
       return sizeof(double);
     case DataType::DELTA_INT32:
diff --git a/deltann/core/utils/misc.h b/deltann/core/misc.h
similarity index 97%
rename from deltann/core/utils/misc.h
rename to deltann/core/misc.h
index 761bf7c2..7ddf0e4a 100644
--- a/deltann/core/utils/misc.h
+++ b/deltann/core/misc.h
@@ -14,8 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ==============================================================================*/
 
-#ifndef DELTANN_UTILS_MISC_H_
-#define DELTANN_UTILS_MISC_H_
+#ifndef DELTANN_CORE_MISC_H_
+#define DELTANN_CORE_MISC_H_
 
 #include <iostream>
 #include <string>
@@ -118,4 +118,4 @@ std::ostream& operator<<(std::ostream& out, const std::vector<T>& v) {
 }
 
 }  // namespace delta
-#endif  // DELTANN_UTILS_MISC_H_
+#endif  // DELTANN_CORE_MISC_H_
diff --git a/deltann/core/runtime.h b/deltann/core/runtime.h
index ceaf6cef..5e43eba9 100644
--- a/deltann/core/runtime.h
+++ b/deltann/core/runtime.h
@@ -27,8 +27,8 @@ limitations under the License.
 #include "core/tflite_model.h"
 #include "core/tfmodel.h"
 #include "core/tfserving_model.h"
-#include "core/utils/config.h"
-#include "core/utils/misc.h"
+#include "core/config.h"
+#include "core/misc.h"
 
 #ifdef USE_TF
 #include "tensorflow/c/c_api.h"
diff --git a/deltann/core/shape.cc b/deltann/core/shape.cc
index 98bcbc96..ab453aa4 100644
--- a/deltann/core/shape.cc
+++ b/deltann/core/shape.cc
@@ -17,7 +17,7 @@ limitations under the License.
 #include <assert.h>
 
 #include "core/shape.h"
-#include "core/utils/logging.h"
+#include "core/logging.h"
 
 namespace delta {
 
diff --git a/deltann/core/tflite_model.h b/deltann/core/tflite_model.h
index 8a33f584..7255cbd1 100644
--- a/deltann/core/tflite_model.h
+++ b/deltann/core/tflite_model.h
@@ -25,8 +25,8 @@ limitations under the License.
 
 #include "core/base_model.h"
 #include "core/data.h"
-#include "core/utils/logging.h"
-#include "core/utils/misc.h"
+#include "core/logging.h"
+#include "core/misc.h"
 
 #include "tensorflow/lite/experimental/c/c_api.h"
 
diff --git a/deltann/core/tfmodel.h b/deltann/core/tfmodel.h
index 8b891160..de79c5ae 100644
--- a/deltann/core/tfmodel.h
+++ b/deltann/core/tfmodel.h
@@ -24,8 +24,8 @@ limitations under the License.
 
 #include "core/base_model.h"
 #include "core/data.h"
-#include "core/utils/logging.h"
-#include "core/utils/misc.h"
+#include "core/logging.h"
+#include "core/misc.h"
 
 #include "tensorflow/cc/saved_model/loader.h"
 #include "tensorflow/cc/saved_model/tag_constants.h"
diff --git a/deltann/core/utils/https.h b/deltann/core/utils/https.h
index ca8e8ef3..5be3cb24 100644
--- a/deltann/core/utils/https.h
+++ b/deltann/core/utils/https.h
@@ -1,4 +1,18 @@
-// https://github.com/HISONA/https_client/blob/master/https.h
+//  Copyright {yyyy} {HISONA}
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+//  https://github.com/HISONA/https_client/blob/master/https.h
 
 #ifndef HTTPS_CLIENT_HTTPS_H
 #define HTTPS_CLIENT_HTTPS_H
diff --git a/deltann/core/utils/https_client.h b/deltann/core/utils/https_client.h
index bf50573f..e4b288a5 100644
--- a/deltann/core/utils/https_client.h
+++ b/deltann/core/utils/https_client.h
@@ -19,8 +19,10 @@ limitations under the License.
 #define DELTANN_CORE_UTILS_HTTPS_CLIENT_H_
 #ifdef USE_TF_SERVING
 
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <string>
+#include <map>
+#include <vector>
 
 #include "core/data.h"
 #include "core/shape.h"
diff --git a/deltann/examples/text_cls/test.cc b/deltann/examples/text_cls/test.cc
index 7f8bb1f5..753c115e 100644
--- a/deltann/examples/text_cls/test.cc
+++ b/deltann/examples/text_cls/test.cc
@@ -17,9 +17,19 @@ limitations under the License.
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
+#include <sys/time.h>
 
 #include "api/c_api.h"
 
+float time_run(InferHandel inf){
+  struct timespec start, end;
+  clock_gettime(CLOCK_MONOTONIC, &start);
+  DeltaRun(inf);
+  clock_gettime(CLOCK_MONOTONIC, &end);
+  return (end.tv_sec - start.tv_sec) + (end.tv_nsec - start.tv_nsec) / 1000000000.0;
+}
+
 int main(int argc, char** argv) {
   // const char* yaml_file = "model.yaml";
   const char* yaml_file = argv[1];
@@ -37,7 +47,9 @@ int main(int argc, char** argv) {
 
   DeltaSetInputs(inf, ins, in_num);
 
-  DeltaRun(inf);
+  // DeltaRun(inf);
+  float dur = time_run(inf);
+  fprintf(stderr, "Duration %04f sec.\n", dur);
 
   int out_num = DeltaGetOutputCount(inf);
   fprintf(stderr, "The output num is %d\n", out_num);
diff --git a/deltann/targets/linux_makefile.inc b/deltann/targets/linux_makefile.inc
index c36cff7e..7d0b613e 100644
--- a/deltann/targets/linux_makefile.inc
+++ b/deltann/targets/linux_makefile.inc
@@ -3,8 +3,8 @@ ifeq ($(TARGET), linux)
     CXX := g++
     CC := gcc
     AR := ar
-    CXXFLAGS += -std=c++11 -fPIC -O3
-    CCFLAGS += -fPIC -O3
+    CXXFLAGS += -fPIC
+    CCFLAGS += -fPIC
 
     ifeq ($(ENGINE),TF)
         $(info this will compile with $(ENGINE))