title: What is C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\index3a0.dat used for?
body: <p>I'm trying to diagnose why out .Net ActiveX control has a much slower load time on certain machines than others and I've discovered (using ProcMon) that on machines that load the control slowly the browser process seems to spend a lot of time doing something with this file.</p>
  
  <p>In the slow process I see groups of events (4-8) in the above format that take around 200ms to complete:</p>
  
  <pre><code>6:02:17.333 CreateFile C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\index3a0.dat NAME NOT FOUND
  6:02:17.364 CreateFile C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\index3a0.dat NAME NOT FOUND
  6:02:17.396 CreateFile C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\index3a0.dat NAME NOT FOUND
  6:02:17.427 CreateFile C:\WINDOWS\assembly\NativeImages_v2.0.50727_32\index3a0.dat NAME NOT FOUND
  </code></pre>
  
  <p>However in a similar trace taken on a machine where the control loads quickly I see only a single line with a <code>SUCCESS</code> result.</p>
  
  <p>What is this file?</p>