title: .NET Garbage Collector difference between x86 / x64. x64 doesn't collect
body: <p>I have a WPF application which doesn't seem to garbage collect on x64 systems. I have tested it carefully on x86 machines and I am confident it isn't a programming problem, the memory usage will grow and then will be garbage collected as I expect.  The target platform = 'Any CPU'</p>
  
  <p>I have discovered that I can eliminate this behaviour on x64 machines by compiling with the target = x86.  x64 or 'Any CPU' fails to release memory.</p>
  
  <p>I also noticed during my investigations that creating a child application domain and manually minimizing the application working set works on x86 but is ignored on x64 systems.  Until I set the target = x86.</p>
  
  <p>Does anyone know why this behaviour exists?  Do we need to avoid 'Any CPU' or x64?</p>