AutoCAD Performance Slowdown

Recently, I had an issue with AutoCAD performance.  Whenever I would pick an entity there was a 3-5 second delay before I could do anything with it.  The issue occurred in both 2011 and 2012 versions.  Usually, when I come across problems like this, I use Process Monitor.  This is a fabulous tool that allows you to view everything that is going on with your computer – it monitors all of the processes:The tool can be a bit overwhelming because, well, you have a lot of things going on with your computer.  If you just want to view what’s going on with AutoCAD, you can filter for the acad.exe process:So now with this filter on, I started searching for the delay when picking entities in AutoCAD.  This is primarily what I was seeing in the process monitor during the delay:

AutoCAD was hanging up while accessing the file mfcm90u.dll.  What is this WinSxS folder?  It’s a critical folder for storage of the operating system components.  Now I have a lead.  Where do I go from here?

Since the problem was happening in different flavors and versions of AutoCAD, and because the mfcm90u.dll file is independent of AutoCAD, I turned my attention away from AutoCAD and towards Windows.  I asked my colleagues if they have any ideas.  One recommended reinstalling the Microsoft Visual C++ Redistributable Package.  I did that – no luck.  I installed Windows 7 Service Pack 1.  Again, no luck.

I disabled McAfee Virus and Spyware Protection.  Luck!  The delay went away.  Good, we’re getting closer.  Disabling AV is obviously not a permanent solution.  Perhaps I can exclude the c:\windows\winsxs folder from the on-access scans.  I’ll try that and report back.