How about with C++ applications?  My C++ solution is about 43 projects with > 5000 files.  Its top level project is a DLL that gets loaded into MS Office applications.  Attaching the debugger to the executable is very, very slow in VS2005 (before and after SP1), especially when using a symbol server.  Most importantly it blocks the IDE until the debugger is attached.

Earlier versions (e.g., 2003) at least did not block the IDE while attaching the debugger.  This allowed you to browse files, set breakpoints, and do other tasks while waiting for the attach to complete.  Sometimes you would even cancel the debugging session BEFORE the attachment was complete if you realized that another change was desired before actually debugging the solution.  None of this is possible anymore because of the IDE block.  I think I've wasted more time with this performance issue than any other (except for maybe the C1023 errors that occur for some unexplicable reason after retrieving code changes from other users in TFS).

Has this been improved of fixed?  I plan on trying 2008 Beta 2 in the near future.