Crystal Report running slow

Hello

We have several crystal reports which are connected to a single SQL database However they are performing really badly. Super Slow. when looking at the sql for the report it shows 10 different queries. the first is the master ones and the rest show as external joins.

there is about 15 tables of data pulled in...so it has merged 6 into a single query

anyone know why it is doing this and how i can get the report to all merge into a single query to save crystal going the data processing itself locally?

Thanks in advance.