Consequences to setting the db compatibility level to SQL Server 2000

We have a Sql Server 2005 DB. For whatever reason, the compatibility level (e.g. via sp_dbcmptlevel) is set to 80 (which is Sql Server 2000).

What are the consequences of that? Is there a performance penalty for my apps because of i开发者_开发知识库t?

See if this helps: Does running a SQL Server 2005 database in compatibility level 80 have a negative impact on performance?

Edit: Not mentioned in the other thread, I think this one is quite interesting as well: http://www.sqlmag.com/Article/ArticleID/49643/sql_server_49643.html