diff -BurN qemu-snapshot-2006-03-27_23.orig/slirp/tcp.h qemu-snapshot-2006-03-27_23/slirp/tcp.h
--- qemu-snapshot-2006-03-27_23.orig/slirp/tcp.h	2004-04-21 17:10:47.000000000 -0700
+++ qemu-snapshot-2006-03-27_23/slirp/tcp.h	2006-04-11 15:22:05.000000000 -0700
@@ -100,8 +100,10 @@
  * With an IP MSS of 576, this is 536,
  * but 512 is probably more convenient.
  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
+ *
+ * We make this 1460 because we only care about Ethernet in the qemu context.
  */
-#define	TCP_MSS	512
+#define	TCP_MSS	1460
 
 #define	TCP_MAXWIN	65535	/* largest value for (unscaled) window */
 
diff -BurN qemu-snapshot-2006-03-27_23.orig/slirp/tcp_input.c qemu-snapshot-2006-03-27_23/slirp/tcp_input.c
--- qemu-snapshot-2006-03-27_23.orig/slirp/tcp_input.c	2004-10-07 16:27:35.000000000 -0700
+++ qemu-snapshot-2006-03-27_23/slirp/tcp_input.c	2006-04-11 15:22:05.000000000 -0700
@@ -580,28 +580,11 @@
 			 *	congestion avoidance sender won't send more until
 			 *	he gets an ACK.
 			 * 
-			 * Here are 3 interpretations of what should happen.
-			 * The best (for me) is to delay-ack everything except
-			 * if it's a one-byte packet containing an ESC
-			 * (this means it's an arrow key (or similar) sent using
-			 * Nagel, hence there will be no echo)
-			 * The first of these is the original, the second is the
-			 * middle ground between the other 2
+			 * It is better to not delay acks at all to maximize
+			 * TCP throughput.  See RFC 2581.
 			 */ 
-/*			if (((unsigned)ti->ti_len < tp->t_maxseg)) {
- */			     
-/*			if (((unsigned)ti->ti_len < tp->t_maxseg && 
- *			     (so->so_iptos & IPTOS_LOWDELAY) == 0) ||
- *			    ((so->so_iptos & IPTOS_LOWDELAY) && 
- *			     ((struct tcpiphdr_2 *)ti)->first_char == (char)27)) {
- */
-			if ((unsigned)ti->ti_len == 1 &&
-			    ((struct tcpiphdr_2 *)ti)->first_char == (char)27) {
-				tp->t_flags |= TF_ACKNOW;
-				tcp_output(tp);
-			} else {
-				tp->t_flags |= TF_DELACK;
-			}
+			tp->t_flags |= TF_ACKNOW;
+			tcp_output(tp);
 			return;
 		}
 	} /* header prediction */
diff -BurN qemu-snapshot-2006-03-27_23.orig/vl.c qemu-snapshot-2006-03-27_23/vl.c
--- qemu-snapshot-2006-03-27_23.orig/vl.c	2006-04-11 15:21:27.000000000 -0700
+++ qemu-snapshot-2006-03-27_23/vl.c	2006-04-11 15:22:05.000000000 -0700
@@ -4026,7 +4026,7 @@
 void main_loop_wait(int timeout)
 {
     IOHandlerRecord *ioh, *ioh_next;
-    fd_set rfds, wfds;
+    fd_set rfds, wfds, xfds;
     int ret, nfds;
     struct timeval tv;
 
@@ -4041,6 +4041,7 @@
     nfds = -1;
     FD_ZERO(&rfds);
     FD_ZERO(&wfds);
+    FD_ZERO(&xfds);
     for(ioh = first_io_handler; ioh != NULL; ioh = ioh->next) {
         if (ioh->fd_read &&
             (!ioh->fd_read_poll ||
@@ -4062,7 +4063,12 @@
 #else
     tv.tv_usec = timeout * 1000;
 #endif
-    ret = select(nfds + 1, &rfds, &wfds, NULL, &tv);
+#if defined(CONFIG_SLIRP)
+    if (slirp_inited) {
+        slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
+    }
+#endif
+    ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
     if (ret > 0) {
         /* XXX: better handling of removal */
         for(ioh = first_io_handler; ioh != NULL; ioh = ioh_next) {