diff --git a/Makefile b/Makefile
index fbba7f3..7e0811d 100644
--- a/Makefile
+++ b/Makefile
@@ -86,7 +86,7 @@ dist: all
 
 IPXWRAPPER_OBJS := src/ipxwrapper.o src/winsock.o src/ipxwrapper_stubs.o src/log.o src/common.o \
 	src/interface.o src/interface2.o src/router.o src/ipxwrapper.def src/addrcache.o src/config.o src/addr.o \
-	src/firewall.o src/ethernet.o src/funcprof.o
+	src/firewall.o src/ethernet.o src/funcprof.o src/coalesce.o
 
 ipxwrapper.dll: $(IPXWRAPPER_OBJS)
 	echo 'const char *version_string = "$(VERSION)", *compile_time = "'`date`'";' | $(CC) -c -x c -o version.o -
diff --git a/src/coalesce.c b/src/coalesce.c
new file mode 100644
index 0000000..16feba6
--- /dev/null
+++ b/src/coalesce.c
@@ -0,0 +1,293 @@
+/* IPXWrapper - Packet coalescing
+ * Copyright (C) 2023 Daniel Collins <solemnwarning@solemnwarning.net>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+#define WINSOCK_API_LINKAGE
+
+#include <uthash.h>
+#include <utlist.h>
+#include <winsock2.h>
+#include <windows.h>
+
+#include "coalesce.h"
+#include "ethernet.h"
+#include "interface.h"
+#include "ipxwrapper.h"
+
+struct coalesce_table_key
+{
+	addr32_t netnum;
+	addr48_t nodenum;
+	uint16_t socket;
+};
+
+typedef struct coalesce_table_key coalesce_table_key;
+
+struct coalesce_dest
+{
+	UT_hash_handle hh;
+	
+	struct coalesce_dest *prev;
+	struct coalesce_dest *next;
+	
+	coalesce_table_key dest;
+	bool active;
+	
+	uint64_t send_timestamps[IPXWRAPPER_COALESCE_PACKET_TRACK_COUNT];
+	
+	uint64_t payload_timestamp;
+	unsigned char payload[IPXWRAPPER_COALESCE_PACKET_MAX_SIZE];
+	int payload_used;
+};
+
+typedef struct coalesce_dest coalesce_dest;
+
+/* coalesce_table provides access to all coalesce_dest structures and should
+ * be iterated using the 'hh' member.
+*/
+static coalesce_dest *coalesce_table = NULL;
+
+/* coalesce_pending provides access to all active coalesce_dest structures
+ * which have data waiting to be transmitted, ordered by insertion date from
+ * oldest to newest.
+*/
+static coalesce_dest *coalesce_pending = NULL;
+
+coalesce_dest *get_coalesce_by_dest(addr32_t netnum, addr48_t nodenum, uint16_t socket)
+{
+	FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_get_coalesce_by_dest]));
+	
+	if(!main_config.dosbox_coalesce)
+	{
+		/* Skip coalescing if disabled. */
+		return NULL;
+	}
+	
+	coalesce_table_key dest = { netnum, nodenum, socket };
+	
+	coalesce_dest *node;
+	HASH_FIND(hh, coalesce_table, &dest, sizeof(dest), node);
+	
+	if(node == NULL)
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_get_coalesce_by_dest_new]));
+		
+		/* TODO: Limit maximum number of nodes, recycle old ones. */
+		
+		node = malloc(sizeof(coalesce_dest));
+		if(node == NULL)
+		{
+			return NULL;
+		}
+		
+		memset(node, 0, sizeof(*node));
+		node->dest = dest;
+		
+		HASH_ADD(hh, coalesce_table, dest, sizeof(node->dest), node);
+	}
+	
+	return node;
+}
+
+bool coalesce_register_send(coalesce_dest *node, uint64_t timestamp)
+{
+	FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_register_send]));
+	
+	memmove(node->send_timestamps, node->send_timestamps + 1, sizeof(node->send_timestamps) - sizeof(*(node->send_timestamps)));
+	node->send_timestamps[IPXWRAPPER_COALESCE_PACKET_TRACK_COUNT - 1] = timestamp;
+	
+	if((node->send_timestamps[0] + IPXWRAPPER_COALESCE_PACKET_START_THRESH) >= timestamp)
+	{
+		return true;
+	}
+	else if(node->active && (node->send_timestamps[0] + IPXWRAPPER_COALESCE_PACKET_STOP_THRESH) < timestamp)
+	{
+		return false;
+	}
+	else{
+		return node->active;
+	}
+}
+
+bool coalesce_add_data(coalesce_dest *cd, const void *data, int size, uint64_t now)
+{
+	FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_add_data]));
+	
+	if(cd->payload_used == 0)
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_add_data_init]));
+		
+		novell_ipx_packet header;
+		
+		header.checksum = 0xFFFF;
+		header.hops = 0;
+		header.type = IPX_MAGIC_COALESCED;
+		
+		addr32_out(header.dest_net, cd->dest.netnum);
+		addr48_out(header.dest_node, cd->dest.nodenum);
+		header.dest_socket = 0;
+		
+		addr32_out(header.src_net, dosbox_local_netnum);
+		addr48_out(header.src_node, dosbox_local_nodenum);
+		header.src_socket = 0;
+		
+		if((sizeof(header) + size) > IPXWRAPPER_COALESCE_PACKET_MAX_SIZE)
+		{
+			return false;
+		}
+		
+		cd->payload_timestamp = now;
+		DL_APPEND(coalesce_pending, cd);
+		
+		memcpy(cd->payload, &header, sizeof(header));
+		cd->payload_used = sizeof(header);
+	}
+	
+	if((cd->payload_used + size) <= IPXWRAPPER_COALESCE_PACKET_MAX_SIZE)
+	{
+		memcpy((cd->payload + cd->payload_used), data, size);
+		cd->payload_used += size;
+		
+		return true;
+	}
+	else{
+		return false;
+	}
+}
+
+void coalesce_flush(coalesce_dest *cd)
+{
+	FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_flush]));
+	
+	assert(cd->payload_used > 0);
+	
+	novell_ipx_packet *header = (novell_ipx_packet*)(cd->payload);
+	header->length = htons(cd->payload_used);
+	
+	log_printf(LOG_DEBUG, "Sending coalesced packet (%d bytes)", cd->payload_used);
+	
+	if(r_sendto(private_socket, (const void*)(cd->payload), cd->payload_used, 0, (struct sockaddr*)(&dosbox_server_addr), sizeof(dosbox_server_addr)) < 0)
+	{
+		log_printf(LOG_ERROR, "Error sending DOSBox IPX packet: %s", w32_error(WSAGetLastError()));
+	}
+	else{
+		__atomic_add_fetch(&send_packets_udp, 1, __ATOMIC_RELAXED);
+		__atomic_add_fetch(&send_bytes_udp, cd->payload_used, __ATOMIC_RELAXED);
+	}
+	
+	cd->payload_used = 0;
+	DL_DELETE(coalesce_pending, cd);
+}
+
+DWORD coalesce_send(const void *data, size_t data_size, addr32_t dest_net, addr48_t dest_node, uint16_t dest_socket)
+{
+	FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_send]));
+	
+	/* We should always be called with an IPX header, even if the
+	 * application is sending zero-byte payloads.
+	*/
+	assert(data_size > 0);
+	
+	uint64_t now = get_uticks();
+	bool queued = false;
+	
+	coalesce_dest *cd = get_coalesce_by_dest(dest_net, dest_node, dest_socket);
+	if(cd != NULL)
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_send_cd]));
+		
+		bool should_coalesce = coalesce_register_send(cd, now);
+		
+		if(should_coalesce && !cd->active)
+		{
+			IPX_STRING_ADDR(dest_addr, dest_net, dest_node, dest_socket);
+			log_printf(LOG_WARNING, "High send rate to %s detected, coalescing future packets\n", dest_addr);
+			
+			cd->active = true;
+		}
+		else if(!should_coalesce && cd->active)
+		{
+			IPX_STRING_ADDR(dest_addr, dest_net, dest_node, dest_socket);
+			log_printf(LOG_INFO, "Send rate to %s has dropped, no longer coalescing packets\n", dest_addr);
+			
+			cd->active = false;
+		}
+		
+		if(
+			should_coalesce
+			&& (cd->payload_used + data_size) > IPXWRAPPER_COALESCE_PACKET_MAX_SIZE
+			&& data_size < (IPXWRAPPER_COALESCE_PACKET_MAX_SIZE / 2))
+		{
+			coalesce_flush(cd);
+		}
+		
+		if(should_coalesce && coalesce_add_data(cd, data, data_size, now))
+		{
+			queued = true;
+		}
+		
+		if(cd->payload_used > 0 && (cd->payload_timestamp + IPXWRAPPER_COALESCE_PACKET_MAX_DELAY) <= now)
+		{
+			coalesce_flush(cd);
+		}
+	}
+	
+	if(!queued)
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_coalesce_send_immediate]));
+		
+		if(r_sendto(private_socket, (const void*)(data), data_size, 0, (struct sockaddr*)(&dosbox_server_addr), sizeof(dosbox_server_addr)) < 0)
+		{
+			DWORD error = WSAGetLastError();
+			log_printf(LOG_ERROR, "Error sending DOSBox IPX packet: %s", w32_error(error));
+			
+			return error;
+		}
+		else{
+			__atomic_add_fetch(&send_packets_udp, 1, __ATOMIC_RELAXED);
+			__atomic_add_fetch(&send_bytes_udp, data_size, __ATOMIC_RELAXED);
+		}
+	}
+	
+	return ERROR_SUCCESS;
+}
+
+void coalesce_flush_waiting(void)
+{
+	uint64_t now = get_uticks();
+	
+	while(coalesce_pending != NULL
+		&& (coalesce_pending->payload_timestamp + IPXWRAPPER_COALESCE_PACKET_MAX_DELAY) <= now)
+	{
+		coalesce_flush(coalesce_pending);
+	}
+}
+
+void coalesce_cleanup(void)
+{
+	while(coalesce_pending != NULL)
+	{
+		coalesce_flush(coalesce_pending);
+	}
+	
+	while(coalesce_table != NULL)
+	{
+		coalesce_dest *cd = coalesce_table;
+		
+		HASH_DEL(coalesce_table, cd);
+		free(cd);
+	}
+}
diff --git a/src/coalesce.h b/src/coalesce.h
new file mode 100644
index 0000000..229f895
--- /dev/null
+++ b/src/coalesce.h
@@ -0,0 +1,59 @@
+/* IPXWrapper - Packet coalescing
+ * Copyright (C) 2023 Daniel Collins <solemnwarning@solemnwarning.net>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+#ifndef IPXWRAPPER_COALESCE_H
+#define IPXWRAPPER_COALESCE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <windows.h>
+
+#include "addr.h"
+
+/* For each destination IPX address, track the timestamp of the past n send
+ * operations, we use this to determine how spammy the application is being
+ * with sendto() calls.
+*/
+#define IPXWRAPPER_COALESCE_PACKET_TRACK_COUNT 512
+
+/* Start coalescing when the rate of send operations to a single IPX address
+ * reaches IPXWRAPPER_COALESCE_PACKET_TRACK_COUNT packets over the past
+ * IPXWRAPPER_COALESCE_PACKET_START_THRESH microseconds.
+*/
+#define IPXWRAPPER_COALESCE_PACKET_START_THRESH 2500000 /* 2.5s */
+
+/* Stop coalescing when the rate of send operations to a single IPX address
+ * falls back under IPXWRAPPER_COALESCE_PACKET_TRACK_COUNT over the past
+ * IPXWRAPPER_COALESCE_PACKET_STOP_THRESH microseconds.
+*/
+#define IPXWRAPPER_COALESCE_PACKET_STOP_THRESH 10000000 /* 10s */
+
+/* Delay the transmission of a packet for coalescing by no more than
+ * IPXWRAPPER_COALESCE_PACKET_MAX_DELAY microseconds.
+*/
+#define IPXWRAPPER_COALESCE_PACKET_MAX_DELAY 20000 /* 20ms */
+
+/* Combine outgoing IPX packets up to IPXWRAPPER_COALESCE_PACKET_MAX_SIZE
+ * bytes of data in the UDP payload.
+*/
+#define IPXWRAPPER_COALESCE_PACKET_MAX_SIZE 1384
+
+DWORD coalesce_send(const void *data, size_t data_size, addr32_t dest_net, addr48_t dest_node, uint16_t dest_socket);
+void coalesce_flush_waiting(void);
+void coalesce_cleanup(void);
+
+#endif /* !IPXWRAPPER_COALESCE_H */
diff --git a/src/config.c b/src/config.c
index 15e6e21..cb2597b 100644
--- a/src/config.c
+++ b/src/config.c
@@ -37,6 +37,7 @@ main_config_t get_main_config(void)
 	
 	config.dosbox_server_addr = NULL;
 	config.dosbox_server_port = 213;
+	config.dosbox_coalesce = false;
 	
 	HKEY reg = reg_open_main(false);
 	
@@ -64,6 +65,7 @@ main_config_t get_main_config(void)
 	
 	config.dosbox_server_addr = reg_get_string(reg, "dosbox_server_addr", "");
 	config.dosbox_server_port = reg_get_dword(reg, "dosbox_server_port", config.dosbox_server_port);
+	config.dosbox_coalesce    = reg_get_dword(reg, "dosbox_coalesce", config.dosbox_coalesce);
 	
 	/* Check for valid frame_type */
 	
@@ -96,7 +98,8 @@ bool set_main_config(const main_config_t *config)
 		&& reg_set_dword(reg, "profile",    config->profile)
 		
 		&& reg_set_string(reg, "dosbox_server_addr", config->dosbox_server_addr)
-		&& reg_set_dword(reg,  "dosbox_server_port", config->dosbox_server_port);
+		&& reg_set_dword(reg,  "dosbox_server_port", config->dosbox_server_port)
+		&& reg_set_dword(reg,  "dosbox_coalesce",    config->dosbox_coalesce);
 	
 	reg_close(reg);
 	
diff --git a/src/config.h b/src/config.h
index b815f31..6fd8570 100644
--- a/src/config.h
+++ b/src/config.h
@@ -50,6 +50,7 @@ typedef struct main_config {
 	
 	char *dosbox_server_addr;
 	uint16_t dosbox_server_port;
+	bool dosbox_coalesce;
 	
 	enum ipx_log_level log_level;
 	bool profile;
diff --git a/src/ipxconfig.cpp b/src/ipxconfig.cpp
index e70da19..a20abf9 100644
--- a/src/ipxconfig.cpp
+++ b/src/ipxconfig.cpp
@@ -53,6 +53,7 @@ enum {
 	
 	ID_DOSBOX_SERVER_ADDR = 51,
 	ID_DOSBOX_SERVER_PORT = 52,
+	ID_DOSBOX_COALESCE = 53,
 	ID_DOSBOX_FW_EXCEPT = 55,
 	
 	ID_IPXWRAPPER_PORT = 61,
@@ -133,6 +134,7 @@ static struct {
 	HWND dosbox_server_addr;
 	HWND dosbox_server_port_lbl;
 	HWND dosbox_server_port;
+	HWND dosbox_coalesce;
 	HWND dosbox_fw_except;
 	
 	HWND box_ipx_options;
@@ -207,6 +209,21 @@ static LRESULT CALLBACK main_wproc(HWND window, UINT msg, WPARAM wp, LPARAM lp)
 						break;
 					}
 					
+					case ID_DOSBOX_COALESCE: {
+						bool coalesce = get_checkbox(wh.dosbox_coalesce);
+						
+						if(coalesce)
+						{
+							int result = MessageBox(NULL, "Packet coalescing requires all players to be using IPXWrapper 0.7.1 or later.\nAre you sure you want to enable it?", "Warning", MB_YESNO | MB_TASKMODAL | MB_ICONWARNING);
+							if(result != IDYES)
+							{
+								set_checkbox(wh.dosbox_coalesce, false);
+							}
+						}
+						
+						break;
+					}
+					
 					case ID_OPT_LOG_DEBUG: {
 						main_window_update();
 						break;
@@ -570,6 +587,7 @@ static bool save_config()
 		}
 		
 		main_config.dosbox_server_port = port;
+		main_config.dosbox_coalesce = get_checkbox(wh.dosbox_coalesce);
 		main_config.fw_except = get_checkbox(wh.dosbox_fw_except);
 	}
 	else if(main_config.encap_type == ENCAP_TYPE_PCAP)
@@ -760,6 +778,7 @@ static void main_window_init()
 		wh.dosbox_server_port_lbl = create_STATIC(wh.box_dosbox_options, "DOSBox IPX server port");
 		wh.dosbox_server_port     = create_child(wh.box_dosbox_options, "EDIT", "", WS_TABSTOP, WS_EX_CLIENTEDGE, ID_DOSBOX_SERVER_PORT);
 		
+		wh.dosbox_coalesce  = create_checkbox(wh.box_dosbox_options, "Coalesce packets when saturated", ID_DOSBOX_COALESCE);
 		wh.dosbox_fw_except = create_checkbox(wh.box_dosbox_options, "Automatically create Windows Firewall exceptions", ID_DOSBOX_FW_EXCEPT);
 		
 		/* Initialise controls. */
@@ -771,6 +790,7 @@ static void main_window_init()
 		sprintf(port_s, "%hu", main_config.dosbox_server_port);
 		SetWindowText(wh.dosbox_server_port, port_s);
 		
+		set_checkbox(wh.dosbox_coalesce, main_config.dosbox_coalesce);
 		set_checkbox(wh.dosbox_fw_except, main_config.fw_except);
 	}
 	
@@ -938,6 +958,9 @@ static void main_window_init()
 		
 		box_dosbox_options_y += text_h; /* Padding. */
 		
+		MoveWindow(wh.dosbox_coalesce, BOX_SIDE_PAD, box_dosbox_options_y, width - 20, text_h, TRUE);
+		box_dosbox_options_y += text_h;
+		
 		MoveWindow(wh.dosbox_fw_except, BOX_SIDE_PAD, box_dosbox_options_y, width - 20, text_h, TRUE);
 		box_dosbox_options_y += text_h;
 		
diff --git a/src/ipxwrapper.c b/src/ipxwrapper.c
index 11070c0..a6d7c54 100644
--- a/src/ipxwrapper.c
+++ b/src/ipxwrapper.c
@@ -57,11 +57,16 @@ struct FuncStats ipxwrapper_fstats[] = {
 	#undef FPROF_DECL
 };
 
+static uint64_t perf_counter_freq = 0;
+
 const unsigned int ipxwrapper_fstats_size = sizeof(ipxwrapper_fstats) / sizeof(*ipxwrapper_fstats);
 
 unsigned int send_packets = 0, send_bytes = 0;  /* Sent from emulated socket */
 unsigned int recv_packets = 0, recv_bytes = 0;  /* Forwarded to emulated socket */
 
+unsigned int send_packets_udp = 0, send_bytes_udp = 0;  /* Sent over UDP transport */
+unsigned int recv_packets_udp = 0, recv_bytes_udp = 0;  /* Received over UDP transport */
+
 static void init_cs(CRITICAL_SECTION *cs)
 {
 	if(!InitializeCriticalSectionAndSpinCount(cs, 0x80000000))
@@ -82,8 +87,17 @@ static void report_packet_stats(void)
 	unsigned int my_recv_packets = __atomic_exchange_n(&recv_packets, 0, __ATOMIC_RELAXED);
 	unsigned int my_recv_bytes   = __atomic_exchange_n(&recv_bytes,   0, __ATOMIC_RELAXED);
 	
+	unsigned int my_send_packets_udp = __atomic_exchange_n(&send_packets_udp, 0, __ATOMIC_RELAXED);
+	unsigned int my_send_bytes_udp   = __atomic_exchange_n(&send_bytes_udp,   0, __ATOMIC_RELAXED);
+	
+	unsigned int my_recv_packets_udp = __atomic_exchange_n(&recv_packets_udp, 0, __ATOMIC_RELAXED);
+	unsigned int my_recv_bytes_udp   = __atomic_exchange_n(&recv_bytes_udp,   0, __ATOMIC_RELAXED);
+	
 	log_printf(LOG_INFO, "IPX sockets sent %u packets (%u bytes)", my_send_packets, my_send_bytes);
 	log_printf(LOG_INFO, "IPX sockets received %u packets (%u bytes)", my_recv_packets, my_recv_bytes);
+	
+	log_printf(LOG_INFO, "UDP sockets sent %u packets (%u bytes)", my_send_packets_udp, my_send_bytes_udp);
+	log_printf(LOG_INFO, "UDP sockets received %u packets (%u bytes)", my_recv_packets_udp, my_recv_bytes_udp);
 }
 
 static DWORD WINAPI prof_thread_main(LPVOID lpParameter)
@@ -104,6 +118,12 @@ BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
 {
 	if(fdwReason == DLL_PROCESS_ATTACH)
 	{
+		LARGE_INTEGER pc_freq;
+		if(QueryPerformanceFrequency(&pc_freq))
+		{
+			perf_counter_freq = pc_freq.QuadPart;
+		}
+		
 		fprof_init(stub_fstats, NUM_STUBS);
 		fprof_init(ipxwrapper_fstats, ipxwrapper_fstats_size);
 		
@@ -111,6 +131,7 @@ BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
 		
 		log_printf(LOG_INFO, "IPXWrapper %s", version_string);
 		log_printf(LOG_INFO, "Compiled at %s", compile_time);
+		log_printf(LOG_INFO, "Performance counter: %lld Hz", perf_counter_freq);
 		
 		if(!getenv("SystemRoot"))
 		{
@@ -308,3 +329,19 @@ uint64_t get_ticks(void)
 		return GetTickCount();
 	}
 }
+
+uint64_t get_uticks(void)
+{
+	LARGE_INTEGER pc_tick;
+	
+	if(perf_counter_freq == 0 || !QueryPerformanceCounter(&pc_tick))
+	{
+		/* Fall back to GetTickCount() if there is no high-resolution
+		 * performance counter available.
+		*/
+		return get_ticks() * 1000;
+	}
+	else{
+		return pc_tick.QuadPart / (perf_counter_freq / 1000000);
+	}
+}
diff --git a/src/ipxwrapper.h b/src/ipxwrapper.h
index 1b7e17c..559e1eb 100644
--- a/src/ipxwrapper.h
+++ b/src/ipxwrapper.h
@@ -150,6 +150,7 @@ struct ipx_packet {
 } __attribute__((__packed__));
 
 #define IPX_MAGIC_SPXLOOKUP 1
+#define IPX_MAGIC_COALESCED 2
 
 typedef struct spxlookup_req spxlookup_req_t;
 
@@ -200,11 +201,15 @@ enum {
 extern unsigned int send_packets, send_bytes;  /* Sent from emulated socket */
 extern unsigned int recv_packets, recv_bytes;  /* Forwarded to emulated socket */
 
+extern unsigned int send_packets_udp, send_bytes_udp;  /* Sent over UDP transport */
+extern unsigned int recv_packets_udp, recv_bytes_udp;  /* Received over UDP transport */
+
 ipx_socket *get_socket(SOCKET sockfd);
 ipx_socket *get_socket_wait_for_ready(SOCKET sockfd, int timeout_ms);
 void lock_sockets(void);
 void unlock_sockets(void);
 uint64_t get_ticks(void);
+uint64_t get_uticks(void);
 
 void add_self_to_firewall(void);
 
diff --git a/src/ipxwrapper_prof_defs.h b/src/ipxwrapper_prof_defs.h
index 052f52a..47c2229 100644
--- a/src/ipxwrapper_prof_defs.h
+++ b/src/ipxwrapper_prof_defs.h
@@ -3,3 +3,19 @@ FPROF_DECL(_handle_udp_recv)
 FPROF_DECL(_handle_dosbox_recv)
 FPROF_DECL(_handle_pcap_frame)
 FPROF_DECL(lock_sockets)
+FPROF_DECL(ioctlsocket_recv_pump)
+FPROF_DECL(ioctlsocket_accumulate)
+FPROF_DECL(recv_pump_select)
+FPROF_DECL(recv_pump_find_slot)
+FPROF_DECL(recv_pump_recv)
+FPROF_DECL(recv_pump_reclaim_socket)
+
+FPROF_DECL(get_coalesce_by_dest)
+FPROF_DECL(get_coalesce_by_dest_new)
+FPROF_DECL(coalesce_register_send)
+FPROF_DECL(coalesce_add_data)
+FPROF_DECL(coalesce_add_data_init)
+FPROF_DECL(coalesce_flush)
+FPROF_DECL(coalesce_send)
+FPROF_DECL(coalesce_send_cd)
+FPROF_DECL(coalesce_send_immediate)
diff --git a/src/router.c b/src/router.c
index 53c660b..0bec648 100644
--- a/src/router.c
+++ b/src/router.c
@@ -25,6 +25,7 @@
 #include <Win32-Extensions.h>
 
 #include "router.h"
+#include "coalesce.h"
 #include "common.h"
 #include "funcprof.h"
 #include "ipxwrapper.h"
@@ -34,6 +35,9 @@
 
 #define IPX_SOCK_ECHO 2
 
+/* Maximum number of packets to dispatch per iteration of the router loop. */
+#define MAX_RECV_PER_LOOP 50
+
 static bool router_running   = false;
 static WSAEVENT router_event = WSA_INVALID_EVENT;
 static HANDLE router_thread  = NULL;
@@ -197,6 +201,8 @@ void router_cleanup(void)
 	
 	/* Release resources. */
 	
+	coalesce_cleanup();
+	
 	if(private_socket != -1)
 	{
 		closesocket(private_socket);
@@ -554,32 +560,88 @@ static void _handle_dosbox_recv(novell_ipx_packet *packet, size_t packet_size)
 		return;
 	}
 	
-	if(min_log_level <= LOG_DEBUG)
+	if(packet->src_socket == 0 && packet->type == IPX_MAGIC_COALESCED)
 	{
-		IPX_STRING_ADDR(src_addr, addr32_in(packet->src_net), addr48_in(packet->src_node), packet->src_socket);
-		IPX_STRING_ADDR(dest_addr, addr32_in(packet->dest_net), addr48_in(packet->dest_node), packet->dest_socket);
+		/* Sanity check the lengths of each inner packet. */
 		
-		log_printf(LOG_DEBUG, "Recieved packet from %s for %s", src_addr, dest_addr);
+		log_printf(LOG_DEBUG, "Recieved coalesced packet (%zu bytes)", packet_size);
+		
+		novell_ipx_packet *inner_packets = (novell_ipx_packet*)(packet->data);
+		size_t remaining_data = packet_size - sizeof(novell_ipx_packet);
+		
+		novell_ipx_packet *end = (novell_ipx_packet*)(packet->data + remaining_data);
+		
+		for(novell_ipx_packet *p = inner_packets; p < end;)
+		{
+			if(remaining_data < sizeof(novell_ipx_packet) || ntohs(p->length) > remaining_data)
+			{
+				/* Doesn't look valid. */
+				log_printf(LOG_ERROR, "Recieved invalid IPX packet from DOSBox server, ignoring");
+				return;
+			}
+			
+			p = (novell_ipx_packet*)((char*)(p) + ntohs(p->length));
+		}
+		
+		/* Deliver the inner packets. */
+		
+		for(novell_ipx_packet *p = inner_packets; p < end;)
+		{
+			if(min_log_level <= LOG_DEBUG)
+			{
+				IPX_STRING_ADDR(src_addr, addr32_in(p->src_net), addr48_in(p->src_node), p->src_socket);
+				IPX_STRING_ADDR(dest_addr, addr32_in(p->dest_net), addr48_in(p->dest_node), p->dest_socket);
+				
+				log_printf(LOG_DEBUG, "Recieved packet from %s for %s", src_addr, dest_addr);
+			}
+			
+			size_t data_size = ntohs(p->length) - sizeof(novell_ipx_packet);
+			
+			_deliver_packet(
+				p->type,
+				
+				addr32_in(p->src_net),
+				addr48_in(p->src_node),
+				p->src_socket,
+				
+				addr32_in(p->dest_net),
+				addr48_in(p->dest_node),
+				p->dest_socket,
+				
+				p->data,
+				data_size);
+			
+			p = (novell_ipx_packet*)((char*)(p) + ntohs(p->length));
+		}
 	}
-	
-	size_t data_size = ntohs(packet->length) - sizeof(novell_ipx_packet);
-	
-	_deliver_packet(
-		packet->type,
+	else{
+		if(min_log_level <= LOG_DEBUG)
+		{
+			IPX_STRING_ADDR(src_addr, addr32_in(packet->src_net), addr48_in(packet->src_node), packet->src_socket);
+			IPX_STRING_ADDR(dest_addr, addr32_in(packet->dest_net), addr48_in(packet->dest_node), packet->dest_socket);
+			
+			log_printf(LOG_DEBUG, "Recieved packet from %s for %s", src_addr, dest_addr);
+		}
 		
-		addr32_in(packet->src_net),
-		addr48_in(packet->src_node),
-		packet->src_socket,
+		size_t data_size = ntohs(packet->length) - sizeof(novell_ipx_packet);
 		
-		addr32_in(packet->dest_net),
-		addr48_in(packet->dest_node),
-		packet->dest_socket,
-		
-		packet->data,
-		data_size);
+		_deliver_packet(
+			packet->type,
+			
+			addr32_in(packet->src_net),
+			addr48_in(packet->src_node),
+			packet->src_socket,
+			
+			addr32_in(packet->dest_net),
+			addr48_in(packet->dest_node),
+			packet->dest_socket,
+			
+			packet->data,
+			data_size);
+	}
 }
 
-static bool _do_udp_recv(int fd)
+static int _do_udp_recv(int fd)
 {
 	struct sockaddr_in addr;
 	int addrlen = sizeof(addr);
@@ -588,14 +650,19 @@ static bool _do_udp_recv(int fd)
 	int len = recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr*)(&addr), &addrlen);
 	if(len == -1)
 	{
-		if(WSAGetLastError() == WSAEWOULDBLOCK || WSAGetLastError() == WSAECONNRESET)
-		{
-			return true;
-		}
+		DWORD err = WSAGetLastError();
 		
-		return false;
+		switch(err)
+		{
+			case WSAEWOULDBLOCK: return 0;
+			case WSAECONNRESET: return 1;
+			default: return -1;
+		}
 	}
 	
+	__atomic_add_fetch(&recv_packets_udp, 1, __ATOMIC_RELAXED);
+	__atomic_add_fetch(&recv_bytes_udp, len, __ATOMIC_RELAXED);
+	
 	if(ipx_encap_type == ENCAP_TYPE_DOSBOX)
 	{
 		if(addr.sin_family != dosbox_server_addr.sin_family
@@ -603,7 +670,7 @@ static bool _do_udp_recv(int fd)
 			|| addr.sin_port != dosbox_server_addr.sin_port)
 		{
 			/* Ignore packet from wrong address. */
-			return true;
+			return 1;
 		}
 		
 		if(dosbox_state == DOSBOX_REGISTERING)
@@ -623,7 +690,7 @@ static bool _do_udp_recv(int fd)
 		_handle_udp_recv((ipx_packet*)(buf), len, addr);
 	}
 	
-	return true;
+	return 1;
 }
 
 static void _handle_pcap_frame(u_char *user, const struct pcap_pkthdr *pkt_header, const u_char *pkt_data)
@@ -766,6 +833,10 @@ static DWORD router_main(void *arg)
 		
 		if(ipx_encap_type == ENCAP_TYPE_DOSBOX)
 		{
+			lock_sockets();
+			coalesce_flush_waiting();
+			unlock_sockets();
+			
 			if(dosbox_state == DOSBOX_DISCONNECTED)
 			{
 				uint64_t now = get_ticks();
@@ -819,14 +890,43 @@ static DWORD router_main(void *arg)
 		}
 		else if(ipx_encap_type == ENCAP_TYPE_DOSBOX)
 		{
-			if(!_do_udp_recv(private_socket))
+			int status = 0;
+			
+			for(int i = 0; i < MAX_RECV_PER_LOOP; ++i)
+			{
+				status = _do_udp_recv(private_socket);
+				if(status <= 0)
+				{
+					break;
+				}
+			}
+			
+			if(status < 0)
 			{
 				exit_status = 1;
 				break;
 			}
 		}
 		else{
-			if(!_do_udp_recv(shared_socket) || !_do_udp_recv(private_socket))
+			int status = 0;
+			
+			for(int i = 0; i < MAX_RECV_PER_LOOP; ++i)
+			{
+				int s1 = _do_udp_recv(shared_socket);
+				int s2 = _do_udp_recv(private_socket);
+				
+				if(s1 < 0 || s2 < 0)
+				{
+					status = -1;
+					break;
+				}
+				else if(s1 == 0 && s2 == 0)
+				{
+					break;
+				}
+			}
+			
+			if(status < 0)
 			{
 				exit_status = 1;
 				break;
diff --git a/src/winsock.c b/src/winsock.c
index 3bb3fac..186739d 100644
--- a/src/winsock.c
+++ b/src/winsock.c
@@ -25,6 +25,7 @@
 #include <wsnwlink.h>
 
 #include "ipxwrapper.h"
+#include "coalesce.h"
 #include "common.h"
 #include "interface.h"
 #include "router.h"
@@ -770,23 +771,18 @@ static BOOL reclaim_socket(ipx_socket *sockptr, int lookup_fd)
 static int recv_pump(ipx_socket *sockptr, BOOL block)
 {
 	int fd = sockptr->fd;
+	u_long available = -1;
 	
 	if(!block)
 	{
-		fd_set read_fds;
-		FD_ZERO(&read_fds);
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_recv_pump_select]));
 		
-		FD_SET(fd, &read_fds);
-		
-		struct timeval timeout = { 0, 0 };
-		
-		int r = r_select(-1, &read_fds, NULL, NULL, &timeout);
-		if(r == -1)
+		if(r_ioctlsocket(fd, FIONREAD, &available) != 0)
 		{
 			unlock_sockets();
 			return -1;
 		}
-		else if(r == 0)
+		else if(available == 0)
 		{
 			/* No packet waiting in underlying recv buffer. */
 			return 0;
@@ -797,15 +793,19 @@ static int recv_pump(ipx_socket *sockptr, BOOL block)
 	
 	int recv_slot = -1;
 	
-	for(int i = 0; i < RECV_QUEUE_MAX_PACKETS; ++i)
 	{
-		if(queue->sizes[i] == IPX_RECV_QUEUE_FREE)
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_recv_pump_find_slot]));
+		
+		for(int i = 0; i < RECV_QUEUE_MAX_PACKETS; ++i)
 		{
-			queue->sizes[i] = IPX_RECV_QUEUE_LOCKED;
-			recv_queue_adjust_refcount(queue, 1);
-			
-			recv_slot = i;
-			break;
+			if(queue->sizes[i] == IPX_RECV_QUEUE_FREE)
+			{
+				queue->sizes[i] = IPX_RECV_QUEUE_LOCKED;
+				recv_queue_adjust_refcount(queue, 1);
+				
+				recv_slot = i;
+				break;
+			}
 		}
 	}
 	
@@ -817,9 +817,19 @@ static int recv_pump(ipx_socket *sockptr, BOOL block)
 	
 	unlock_sockets();
 	
-	int r = r_recv(fd, (char*)(queue->data[recv_slot]), MAX_PKT_SIZE, 0);
+	int r;
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_recv_pump_recv]));
+		r = r_recv(fd, (char*)(queue->data[recv_slot]), MAX_PKT_SIZE, 0);
+	}
 	
-	if(!reclaim_socket(sockptr, fd))
+	bool ok;
+	{
+		FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_recv_pump_reclaim_socket]));
+		ok = reclaim_socket(sockptr, fd);
+	}
+	
+	if(!ok)
 	{
 		/* The application closed the socket while we were in the recv() call.
 		 * Just discard our handle, let the queue be destroyed.
@@ -1375,7 +1385,14 @@ static int send_packet(const ipx_packet *packet, int len, struct sockaddr *addr,
 		log_printf(LOG_DEBUG, "Sending packet from %s to %s (%s:%hu)", src_addr, dest_addr, inet_ntoa(v4->sin_addr), ntohs(v4->sin_port));
 	}
 	
-	return (r_sendto(private_socket, (char*)packet, len, 0, addr, addrlen) == len);
+	int r = r_sendto(private_socket, (char*)packet, len, 0, addr, addrlen);
+	if(r == len)
+	{
+		__atomic_add_fetch(&send_packets_udp, 1, __ATOMIC_RELAXED);
+		__atomic_add_fetch(&send_bytes_udp, len, __ATOMIC_RELAXED);
+	}
+	
+	return r;
 }
 
 static DWORD ipx_send_packet(
@@ -1527,14 +1544,9 @@ static DWORD ipx_send_packet(
 			
 			memcpy(packet->data, data, data_size);
 			
-			DWORD error = ERROR_SUCCESS;
-			
-			if(r_sendto(private_socket, (const void*)(packet), packet_size, 0, (struct sockaddr*)(&dosbox_server_addr), sizeof(dosbox_server_addr)) < 0)
+			DWORD error = coalesce_send(packet, packet_size, dest_net, dest_node, dest_socket);
+			if(error == ERROR_SUCCESS)
 			{
-				error = WSAGetLastError();
-				log_printf(LOG_ERROR, "Error sending DOSBox IPX packet: %s", w32_error(error));
-			}
-			else{
 				__atomic_add_fetch(&send_packets, 1, __ATOMIC_RELAXED);
 				__atomic_add_fetch(&send_bytes, data_size, __ATOMIC_RELAXED);
 			}
@@ -1810,28 +1822,36 @@ int PASCAL ioctlsocket(SOCKET fd, long cmd, u_long *argp)
 		
 		if(cmd == FIONREAD && !(sock->flags & IPX_IS_SPX))
 		{
-			while(1)
 			{
-				int r = recv_pump(sock, FALSE);
-				if(r < 0)
-				{
-					/* Error in recv_pump() */
-					return -1;
-				}
+				FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_ioctlsocket_recv_pump]));
 				
-				if(r == 0)
+				while(1)
 				{
-					/* No more packets ready to read from underlying socket. */
-					break;
+					int r = recv_pump(sock, FALSE);
+					if(r < 0)
+					{
+						/* Error in recv_pump() */
+						return -1;
+					}
+					
+					if(r == 0)
+					{
+						/* No more packets ready to read from underlying socket. */
+						break;
+					}
 				}
 			}
 			
 			unsigned long accumulated_packet_data = 0;
 			
-			for(int i = 0; i < sock->recv_queue->n_ready; ++i)
 			{
-				const ipx_packet *packet = (const ipx_packet*)(sock->recv_queue->data[ sock->recv_queue->ready[i] ]);
-				accumulated_packet_data += packet->size;
+				FPROF_RECORD_SCOPE(&(ipxwrapper_fstats[IPXWRAPPER_FSTATS_ioctlsocket_accumulate]));
+				
+				for(int i = 0; i < sock->recv_queue->n_ready; ++i)
+				{
+					const ipx_packet *packet = (const ipx_packet*)(sock->recv_queue->data[ sock->recv_queue->ready[i] ]);
+					accumulated_packet_data += packet->size;
+				}
 			}
 			
 			unlock_sockets();