diff --git a/bindings/cpp/CMakeLists.txt b/bindings/cpp/CMakeLists.txt
index 05c58ea7..a8f527ed 100644
--- a/bindings/cpp/CMakeLists.txt
+++ b/bindings/cpp/CMakeLists.txt
@@ -32,7 +32,7 @@ find_package(Threads REQUIRED)
 find_package(Arrow REQUIRED)
 
 if (NOT CMAKE_BUILD_TYPE)
-    set(CMAKE_BUILD_TYPE Debug)
+    set(CMAKE_BUILD_TYPE Release)
 endif()
 
 set(CMAKE_CXX_STANDARD 17)
@@ -122,4 +122,4 @@ add_dependencies(fluss_cpp cargo_build)
 if (FLUSS_ENABLE_ADDRESS_SANITIZER)
     target_compile_options(fluss_cpp PRIVATE -fsanitize=leak,address,undefined -fno-omit-frame-pointer -fno-common -O1)
     target_link_options(fluss_cpp PRIVATE -fsanitize=leak,address,undefined)
-endif()
\ No newline at end of file
+endif()
diff --git a/bindings/cpp/README.md b/bindings/cpp/README.md
index 539e3130..1a8d9f2f 100644
--- a/bindings/cpp/README.md
+++ b/bindings/cpp/README.md
@@ -22,12 +22,15 @@ cmake ..
 cmake --build .
 ```
 
+By default, CMake now uses `Release` when `CMAKE_BUILD_TYPE` is not specified.
+
 **With Bazel:**
 
 ```bash
 cd bindings/cpp
 bazel build //...
 ```
+`ci.sh` defaults to optimized builds via `-c opt` (override with `BAZEL_BUILD_FLAGS` if needed).
 See [ci.sh](ci.sh) for the CI build sequence.
 
 
diff --git a/bindings/cpp/ci.sh b/bindings/cpp/ci.sh
index b5eb9676..ebf5f092 100755
--- a/bindings/cpp/ci.sh
+++ b/bindings/cpp/ci.sh
@@ -19,6 +19,7 @@
 set -xe 
 
 DIR="$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
+BAZEL_BUILD_FLAGS="${BAZEL_BUILD_FLAGS:--c opt}"
 
 # Set Bazel output base to bazel-build directory
 # This ensures all Bazel outputs are in bazel-build/.bazel-output-base
@@ -33,16 +34,16 @@ bazel() {
 }
 
 compile() {
-    bazel build //:fluss_cpp
+    bazel build ${BAZEL_BUILD_FLAGS} //:fluss_cpp
 }
 
 build_example() {
-    bazel build //:fluss_cpp_example
+    bazel build ${BAZEL_BUILD_FLAGS} //:fluss_cpp_example
 }
 
 run_example() {
     build_example
-    bazel run //:fluss_cpp_example
+    bazel run ${BAZEL_BUILD_FLAGS} //:fluss_cpp_example
 }
 
 clean() {