I agree with everyone else.
I went to the link on MSDN to read about this, and it says basically that it "might" have an impact.
I've read the article as well saying 3-5% based on system.
I've got about 20 systems using TDE, if there are some metrics or data saying this does effect databases and here are some examples I'd like to see it.
Depending on load, depending on server resources, depending on instance build, depending on TempDB being on a dedicated disk with multiple datafiles, there is a lot that needs to be quantified before this question can be made black and white.
Not to mention that TDE uses the Windows API to encrypt the files on disk. Pages in memory are NOT encrypted, the TempDB files in memory would feel no ill effect from this if they have enough memory to opperate in. this would effect a server during the checkpoint where all pages are flushed to the disk. Which once again depending on how the server is sized, the load in place, and the volume of users may make a little, a lot, or no difference whatsoever.
the wording is also confusing, but I dislike the question because it makes a statement and then gives you litteraly no info to back it up.
the TDE page on MSDN links to the Understanding the TempDB page on MSDN which has absoluetly nothing on it regarding TDE.
I get it that Microsoft put it on MSDN, but come on flush out a question before you make a statement.