Regarding
http://trac.xbmc.org/ticket/14408 referring to the thread
http://forum.xbmc.org/showthread.php?tid=166558 (this thread)
I can confirm that on my XP SP3 laptop from 2005 all recent nightlies are very slow (unusable) and can't always be killed.
I know, I need a new PC. Or Mac. Or Linux. But actually I like XP (and dislike windows 8)
I can also confirm that "xbmc-13.0-Gotham_alpha4.exe" is a version that works on my old laptop.
I'd like to help. But it makes my PC hang so hard I need to push the power button. So I thought: what if I could reproduce this in a virtual machine?
This is what I tried: Install XP SP3 (dutch) in Virtualbox 4.2.16.
Enable directx3d support by installing this option in guest additions (boot guest in safe mode, install guest additions)
Increase guest video memory to 128 MB and enable 3D and 2D acceleration.
Install "xbmc-13.0-Gotham_alpha4.exe" and connect to a Synology UPNP share. Works as expected.
Install "XBMCSetup-20130819-0efa87e-3127.exe": symptoms as described by original poster. Extremely slow/unresponsive.
So, now I can test a bit more "freely". But what is the next step? All hints welcome. I'll try to "read" the change set that caused the issue, but I am not an expert programmer.