Index: /trunk/src/VBox/Devices/Network/slirp/bsd/kern/kern_mbuf.c
===================================================================
--- /trunk/src/VBox/Devices/Network/slirp/bsd/kern/kern_mbuf.c	(revision 30350)
+++ /trunk/src/VBox/Devices/Network/slirp/bsd/kern/kern_mbuf.c	(revision 30351)
@@ -126,5 +126,13 @@
 	nmbjumbop = nmbclusters / 2;
 	nmbjumbo9 = nmbjumbop / 2;
+#ifndef VBOX
 	nmbjumbo16 = nmbjumbo9 / 2;
+#else
+    /* drvNATNetowrkUp_AllocBuf always requests mbuf from this 
+     * zones, that require more buffers allocated on jumbo16 zone,
+     * in case of intensive communication like p2p and UDP benches. 
+     */
+    nmbjumbo16 = nmbclusters;
+#endif
 	TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
 }