Salesforce retrieve attachments very slow


We are trying to use cloudstreams to retrieve attachments from Salesforce.
This operation using the salesforce APIs directly with soapUI takes less 1 second to send 3 documents (total size < 1Mo). Using Cloudstreams, the same retrieval takes more than 10 seconds… Ouch!
The more documents there are to retrieve, the longer it takes with cloudstreams.

Did anyone already encounter the same problem, and was able to find a solution?

Thanks in advance for your replies!