Feb 17, 2015 09:34 AM|Siva Krishna Macha|LINK
As per the above description, it looks like there is no problem for your WCF service configuration but the slowless is due to the complex business logic involved.
You would need to look at your design to make it more simple. The solutions would depend on your requirement.
Similarly if you want to use these calls from server side, you can think of calling these methods in parallel (If you are using more than one call and if those are independent for your logic).
You can also think to see if you can further separate those methods into multiple small functions and use the only function required for the specific use case.
If there are some file related things, you can think of Streaming options, etc.