title: Xcode 4.2 is very slow to save a file / frequently beach-balls
body: <p>I am using Xcode 4.2 for Lion / production version.  the previous version of Xcode 4 performed just fine.</p>
  
  <p>every time i save a file and sometimes randomly, the beach-ball shows for 5-10 seconds for no apparent reason.</p>
  
  <p>i am using subversion for what its worth.</p>
  
  <p>i captured a sample and it seems to be somewhere in here:</p>
  
  <pre><code>1775 Thread_791676   DispatchQueue_1: com.apple.main-thread  (serial)
  + 1775 ???  (in Xcode)  load address 0x103392000 + 0xeec  [0x103392eec]
  +   1775 NSApplicationMain  (in AppKit) + 867  [0x7fff9684180c]
  +     1775 -[NSApplication run]  (in AppKit) + 555  [0x7fff965c2682]
  +       1775 -[IDEApplication sendEvent:]  (in IDEKit) + 366  [0x103c95b71]
  +         1775 -[NSApplication sendEvent:]  (in AppKit) + 4282  [0x7fff9662c170]
  +           1775 -[NSApplication _handleKeyEquivalent:]  (in AppKit) + 526  [0x7fff9673488d]
  +             1775 -[NSMenu performKeyEquivalent:]  (in AppKit) + 281  [0x7fff96735c3a]
  +               1775 CFRunLoopRunSpecific  (in CoreFoundation) + 230  [0x7fff8e744ae6]
  +                 1775 __CFRunLoopRun  (in CoreFoundation) + 1724  [0x7fff8e7454dc]
  +                   1775 _dispatch_main_queue_callback_4CF  (in libdispatch.dylib) + 308  [0x7fff8c3ba72a]
  +                     1775 _dispatch_call_block_and_release  (in libdispatch.dylib) + 18  [0x7fff8c3b88ba]
  +                       1775 __-[NSDocumentController(NSInternal) _onMainThreadInvokeWorker:]_block_invoke_3  (in AppKit) + 492  [0x7fff96995333]
  +                         1775 __-[NSDocument performAsynchronousFileAccessUsingBlock:]_block_invoke_6  (in AppKit) + 94  [0x7fff96964cad]
  +                           1775 -[IDEEditorDocument continueFileAccessUsingBlock:]  (in IDEKit) + 71  [0x103db69db]
  +                             1775 -[NSDocument continueFileAccessUsingBlock:]  (in AppKit) + 227  [0x7fff96964898]
  +                               1775 __-[NSDocument saveToURL:ofType:forSaveOperation:completionHandler:]_block_invoke_1  (in AppKit) + 845  [0x7fff96969702]
  +                                 1775 -[NSDocument _fileCoordinator:coordinateReadingContentsAndWritingItemAtURL:byAccessor:]  (in AppKit) + 248  [0x7fff9697b25c]
  +                                   1775 -[NSFileCoordinator(NSPrivate) _coordinateReadingItemAtURL:options:writingItemAtURL:options:error:byAccessor:]  (in Foundation) + 829  [0x7fff96471e65]
  +                                     1775 -[NSFileCoordinator(NSPrivate) _invokeAccessor:orDont:thenRelinquishAccessClaimForID:]  (in Foundation) + 207  [0x7fff9646ea8d]
  +                                       1775 __-[NSDocument saveToURL:ofType:forSaveOperation:completionHandler:]_block_invoke_7  (in AppKit) + 1313  [0x7fff96985c80]
  +                                         1775 __-[NSDocument saveToURL:ofType:forSaveOperation:completionHandler:]_block_invoke_14  (in AppKit) + 502  [0x7fff9698535a]
  +                                           1775 -[NSDocument _preserveContentsIfNecessaryAfterWriting:toURL:forSaveOperation:version:error:]  (in AppKit) + 286  [0x7fff9697b004]
  +                                             1775 -[NSDocument _preserveContentsOfURL:forReason:comment:options:error:]  (in AppKit) + 335  [0x7fff96978c88]
  +                                               1775 -[NSFileVersion(NSPrivate) _setDocumentInfo:]  (in Foundation) + 54  [0x7fff9648e905]
  +                                                 1775 GSLibrarySetGenerationInfoValueForKey  (in GenerationalStorage) + 620  [0x7fff8eab60bf]
  +                                                   1775 ipc_set_info_value  (in GenerationalStorage) + 250  [0x7fff8eaa714d]
  +                                                     1775 mach_msg  (in libsystem_kernel.dylib) + 73  [0x7fff95131d71]
  +                                                       1775 mach_msg_trap  (in libsystem_kernel.dylib) + 10  [0x7fff9513267a]
  </code></pre>