It has been a number of years since I have seen a TempDB contention issue in a system that I support. When I came across this one, luckily during a load test and not a production environment, it was a great refresher.  The offending application in this case is SharePoint 2010, but the problem was due to a customization/configuration exceeding a known limitation within SharePoint. I will start off by discussing how to diagnose the issue from a SQL perspective regardless of the offending application...