Without going into great technical detail (which on this topic I couldn’t do anyway), it seems after much reading that it is a recommended practice to spread you SQL Server TempDB across multiple files based on how many cores (or perhaps threads) your processor has.

To keep things simple, let’s say I have a 4 core CPU and no hyper-threading (I am not sure if the rule applies to physical cores or to threads), this means I want to split my TempDB up into four different files. However there is one caveat, you should only do this if you actually have four separate physical drives. Not separate files on one drive, not even separate files on separate partitions… this is only beneficial if you actually have separate physical drives based on what I read.