title: optimizeCompilations="true" doesn't seem to be working
body: <p>I have a web application project referencing other projects and dll.  A while back, we had added the optimizeCompilations="true" flag to the web.config in order to decrease the wait time for the initial page refresh after making changes to one of the related files.  We got the wait time down to about 15-20 seconds.</p>
  
  <p>However, at some point, wait got much longer and I can't figure out what's the cause.  I read a bunch of articles on that flag and know one really describes how it determines when to recompile the entire site inside the Framework temp folder.  It seems that no matter what I recompile whether it be a referenced dlls or the web app dll itself, when I visit the first page, the entire contents of the framework temp folder get's recreated taking about 90 seconds.</p>
  
  <p>Is there anyway to trackdown what's causing this.</p>
  
  <p>On thing that makes me thing the optimizeCompilation flag is not working is that when it was working, occassionally we would run into one of those side cases where a change would require the entire site to be updated and we would get an error.  At that point we had to do a rebuild to fix it. I can't remember the last time that has happened.</p>
  
  <p>The way I understand it, even if the Dlls change in the root, the entire site will NOT recompile if that flag is set.</p>
  
  <p>Also, I found something odd.  In the framework temp folder for the web site, there's a hash.web file containing a hash code.  I'm assuming this is the code the compiler uses to see if something changed.  As a test, I recorded that code, made a change to a source file and compiled. I then checked the bin folder and noted that the only changed files were a few DLLs.  I refreshed my web page in my broswer and it took over a minute to refresh. I then checked the framework temp folder and mostly all the files had the current data, meaning they were all recompiled.  However, when I checked the hash code in hash.web, it was the same.  I would have thought that would have been different.</p>