High CPU utilisation on the data tier after a TFS 2010 to 2013 upgrade
There have been significant changes in the DB schema between TFS 2010 and 2013. This means that as part of an in-place upgrade process a good deal of data needs to be moved around. Some of this is done as part of the actual upgrade process, but to get you up and running quicker, some is done post upgrade using SQL SPROCs. Depending how much data there is to move this can take a while, maybe many hours....