Tempdb contention has long been an issue in SQL Server, and there are many blogs on the issue already. But I wanted to add one more mainly to highlight the improvements in recent versions of SQL Server
Tempdb contention is most often discussed in as relating to the creation of temp tables (and other objects) in tempdb. If you are experiencing this you will see PAGELATCH_EX or PAGELATCH_SH waits, frequently with wait resources like 2:1:1 or 2:1:3. This indicates contention in database 2 (tempdb), page 1 (the first data file in tempdb), and one of the PFS, GAM, or SGAM pages (which are pages 1, 2, and 3 respectively). Tempdb files of sufficient size will have additional PFS, GAM, and SGAM pages at higher page numbers, but 1 and 3 are the pages most often referenced.
Read on to see what the SQL Server team has done over three of the past four versions of SQL Server to limit tempdb contention.