diff --git a/onnxruntime/core/framework/kernel_def_builder.cc b/onnxruntime/core/framework/kernel_def_builder.cc
index 6270e30d3e..9aa8ecf787 100644
--- a/onnxruntime/core/framework/kernel_def_builder.cc
+++ b/onnxruntime/core/framework/kernel_def_builder.cc
@@ -15,7 +15,7 @@ inline bool AreIntervalsOverlap(int start1, int end1, int start2, int end2) {
 
 template <typename T>
 inline bool AreVectorsOverlap(const std::vector<T>& v1, const std::vector<T>& v2) {
-  for (T type : v1) {
+  for (const T& type : v1) {
     if (std::find(v2.begin(), v2.end(), type) != v2.end()) {
       return true;
     }
@@ -44,7 +44,7 @@ bool KernelDef::IsConflict(const KernelDef& other) const {
   //only one case they don't conflict:
   //There is a type_constraint, it exists in both hands, but they don't overlap
   //check types
-  auto other_types = other.TypeConstraints();
+  const auto& other_types = other.TypeConstraints();
   bool type_has_conflict = true;
   for (const auto& it : type_constraints_) {
     auto iter = other_types.find(it.first);
diff --git a/onnxruntime/core/graph/model.cc b/onnxruntime/core/graph/model.cc
index 24f45250eb..f88427b5e9 100644
--- a/onnxruntime/core/graph/model.cc
+++ b/onnxruntime/core/graph/model.cc
@@ -26,8 +26,6 @@ using namespace ONNX_NAMESPACE;
 using namespace onnxruntime;
 using namespace onnxruntime::common;
 
-static constexpr int protobuf_block_size_in_bytes = 4 * 1024 * 1024;
-
 namespace onnxruntime {
 Model::Model(const std::string& graph_name,
              bool is_onnx_domain_only,
@@ -239,7 +237,7 @@ Status Model::Load(std::istream& model_istream, ModelProto* p_model_proto) {
   if (!p_model_proto) {
     return Status(ONNXRUNTIME, INVALID_ARGUMENT, "Null model_proto ptr.");
   }
-  google::protobuf::io::IstreamInputStream zero_copy_input(&model_istream, protobuf_block_size_in_bytes);
+  google::protobuf::io::IstreamInputStream zero_copy_input(&model_istream);
   const bool result = p_model_proto->ParseFromZeroCopyStream(&zero_copy_input) && model_istream.eof();
   if (!result) {
     return Status(ONNXRUNTIME, INVALID_PROTOBUF, "Failed to load model because protobuf parsing failed.");
@@ -449,7 +447,7 @@ Status Model::Load(int fd, ONNX_NAMESPACE::ModelProto& model_proto) {
   }
 
 #if GOOGLE_PROTOBUF_VERSION >= 3002000
-  FileInputStream input(fd, protobuf_block_size_in_bytes);
+  FileInputStream input(fd);
   const bool result = model_proto.ParseFromZeroCopyStream(&input) && input.GetErrno() == 0;
   if (!result) {
     return Status(ONNXRUNTIME, INVALID_PROTOBUF, "Protobuf parsing failed.");