diff --git a/libvirt.cpp b/libvirt.cpp
index 6c3260c..0a14e5c 100644
--- a/libvirt.cpp
+++ b/libvirt.cpp
@@ -123,15 +123,15 @@ bool LibVirt::LaunchMachine(const char* XmlFileName, const char* BootDevice)
     xmlFreeDoc(xml);
     xmlXPathFreeContext(ctxt);
 
-    if (!PrepareSerialPort())
-    {
-        return false;
-    }
-
     vDom = virDomainDefineXML(vConn, buffer);
     xmlFree((xmlChar*)buffer);
     if (vDom)
     {
+        if (!PrepareSerialPort())
+        {
+            return false;
+        }
+
         if (virDomainCreate(vDom) != 0)
         {
             virDomainUndefine(vDom);
diff --git a/virtualbox.cpp b/virtualbox.cpp
index ef191f3..120fd22 100644
--- a/virtualbox.cpp
+++ b/virtualbox.cpp
@@ -32,6 +32,12 @@ void VirtualBox::InitializeDisk()
 
 bool VirtualBox::PrepareSerialPort()
 {
+    char vboxmanage_cmdline[300];
+
+    /* VirtualBox 5.x serial port output is unbearably slow by default, fix that! */
+    sprintf(vboxmanage_cmdline, "VBoxManage setextradata %s VBoxInternal/Devices/serial/0/Config/YieldOnLSRRead 1", AppSettings.Name);
+    Execute(vboxmanage_cmdline);
+
     return CreateLocalSocket();
 }