All you did by detaching the database was flush queries out of the cache (and probably flushed data out of the cache too). That's not a solution. Instead, you need to set up monitoring on your server in order to understand where the bottlenecks are coming from. Then, usually, you have to look at the code of the queries to see what's going wrong. All these topics are covered in the books in my signature below. With such a generic question, that's all the information I can suggest.