Why do SQL FullText queries slow down when you OR?

Question

In SQL Server (2008), I have a FullText index on two columns, call them Table1.FirstNames and Table2.LastNames. After profiling some queries, I came u

Answer 1

Does changing to using ContainsTable help?

It did here Adding more OR searches with CONTAINS Brings Query to Crawl

And the same answerer (Joe Stefanelli) managed to bring about a similar improvement by changing FREETEXT predicates combined with OR to a FREETEXTTABLE here SQL Server full text query across multiple tables - why so slow?