There are many reasons why your Db might be slow.,

chcek if there is any long running transaction using DBCC OPENTRAN ('DBNAME') , if u r DBA get ur dev and ask him about this transaction and if it all it can be kill, kill the transaction else wait for its course to complete , check your network latency, u r temp db , if mirroring is transactional u need t ocehck ur mirroring status,