We have a web app that was migrated from SharePoint 2007 to 2010 and then to 2013 using Database attach and restore method.
What we have seen is that the performance is not quite what we expected on SP 2013. We believe that this is due to the junk we carried from 2007 versions.
One of them being BLOB's which comes up with extensive usage of document libraries.
As we had done Database upgrade, the existing content does not use the shredded storage feature of SP 2013.
What would be other features/issues that carry forward from previous versions of SharePoint and persist (at least in existing content) even on the newer environment?
This would help us in cleaning or perform an upgrade using 3rd party tool.