diff --git a/trunk/src/app/srs_app_config.hpp b/trunk/src/app/srs_app_config.hpp
index 34315406c..1ec0e2411 100644
--- a/trunk/src/app/srs_app_config.hpp
+++ b/trunk/src/app/srs_app_config.hpp
@@ -539,6 +539,7 @@ public:
     * get the mr sleep time in ms for vhost.
     * @param vhost, the vhost to get the mr sleep time.
     */
+    // TODO: FIXME: add utest for mr config.
     virtual int                 get_mr_sleep_ms(std::string vhost);
 private:
     /**
diff --git a/trunk/src/app/srs_app_recv_thread.cpp b/trunk/src/app/srs_app_recv_thread.cpp
index 0226090c2..578bc842e 100644
--- a/trunk/src/app/srs_app_recv_thread.cpp
+++ b/trunk/src/app/srs_app_recv_thread.cpp
@@ -33,6 +33,9 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 using namespace std;
 
+// the max small bytes to group
+#define SRS_MR_SMALL_BYTES 4096
+
 ISrsMessageHandler::ISrsMessageHandler()
 {
 }
@@ -390,8 +393,8 @@ void SrsPublishRecvThread::update_buffer(bool mr_enabled, int sleep_ms)
     // TODO: FIXME: refine it.
     
 #ifdef SRS_PERF_MERGED_READ
-    // previous enabled mr, update the buffer.
-    if (mr && mr_sleep != sleep_ms) {
+    // update the buffer.
+    if (true) {
         // the underlayer api will set to SRS_MR_SOCKET_BUFFER bytes.
         //      4KB=4096, 8KB=8192, 16KB=16384, 32KB=32768, 64KB=65536, 
         //      128KB=131072, 256KB=262144, 512KB=524288
diff --git a/trunk/src/core/srs_core_performance.hpp b/trunk/src/core/srs_core_performance.hpp
index 29abcbbb7..6407ae8df 100644
--- a/trunk/src/core/srs_core_performance.hpp
+++ b/trunk/src/core/srs_core_performance.hpp
@@ -56,9 +56,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * That is, the latency is 120ms(the sleep time).
 */
 // to enable merged read.
-#undef SRS_PERF_MERGED_READ
-// the max sleep time in ms
-#define SRS_MR_MAX_SLEEP_MS 800
+#define SRS_PERF_MERGED_READ
 
 /**
 * the send cache time in ms.
diff --git a/trunk/src/rtmp/srs_protocol_buffer.cpp b/trunk/src/rtmp/srs_protocol_buffer.cpp
index 4a8234dba..ab0cc7bbd 100644
--- a/trunk/src/rtmp/srs_protocol_buffer.cpp
+++ b/trunk/src/rtmp/srs_protocol_buffer.cpp
@@ -28,10 +28,8 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <srs_kernel_utility.hpp>
 #include <srs_core_performance.hpp>
 
-// the max small bytes to group
-#define SRS_MR_SMALL_BYTES 4096
 // the default recv buffer size
-#define SRS_DEFAULT_RECV_BUFFER_SIZE 8192
+#define SRS_DEFAULT_RECV_BUFFER_SIZE 32768
 
 // the max header size,
 // @see SrsProtocol::read_message_header().
@@ -111,7 +109,9 @@ void SrsFastBuffer::set_buffer(int buffer_size)
     int cap = end - p;
     
     char* buf = new char[buffer_size];
-    memcpy(buf, buffer, nb_buffer);
+    if (cap > 0) {
+        memcpy(buf, buffer, nb_buffer);
+    }
     srs_freep(buffer);
     
     buffer = buf;