title: NSIS Installer slow on machine with Microsoft Security Essentials
body: <p>So I've got an issue where our NSIS installers slow down heaps when installing over the top of an existing installation?  </p>
  
  <p>It seems to be directly related to Microsoft's Security Essentials and turning off runtime checking causes it to go away, but I've never encountered anything similar with any other installers - so is there a known issue here or should we be doing things differently to avoid this kind of thing?</p>
  
  <p>To give you an idea how slow.. each .EXE takes 10-15 seconds to unpack but on a clean machine or with Security Essentials turned off it takes only a second or two - and this is on the a top of the line core i7 with 12GB of ram.</p>
  
  <p>Only thing I can think of is to copy the exe to a temporary file and then move it over afterwards, but this seems a bit clunky.</p>