title: STS slow build when loading xyz-context.xml files
body: <p>i recently started using STS on a 64 bit Windows machine. Often when i "clean" my project STS gets unresponsive or just takes minutes to build while loading context.xml. files.
  How can I fix this?  Is it looking for resources on the web and waiting for timeouts.?</p>
  
  <p>EDIT: I noticed that during the build process my network usage goes up. Not sure yet what is going on there...</p>
  
  <p>EDIT: Possibly STS is loading all of the referenced springsource XSD files for XML validation?`If so, how can I disable this validation (apart from copying the files and referencing them locally, of course)? I've already tried disabling all of the Preferences related to "Validation" in STS - to no avail.</p>