I agree with tommyh, the word 'great' is misleading in this context.

Not being a native English speaker, I deciphered that sentence as 'Performance will greatly decrease if tempdb is encrypted'. After that I googled 'transparent data encryption performance' and found this article: http://www.databasejournal.com/features/mssql/article.php/3815501/Performance-Testing-SQL-2008s-Transparent-Data-Encryption.htm

Rob Garrison, the author of the article, emulated an OLTP environment and found that the average TDE overhead was 6.36%. Should this number be considered as 'great'? I don't think so 🙂

The correct answer should be 'none of the above', because:

– 'the Tempdb also automatically gets encrypted on that instance' – true;

– 'this could have a great performace effect for the other unencrypted databases' – false.