Azure cloud generator to test SAP


I need to test a SAP-ISU system, hosted on Azure. We want to use Load generators (Windows) that are also in Azure, sized 8 cores 32 Gig memory. I assumed that were pretty powerfull systems, but we find that we can not run more than 10 users on each machines before the SAP Gui time on the application server becomes much to high. Does  anybody have any advice on how this could be improved, are there best practises that I should follow? We will need now 20 Azure machines for the test, and that is something that will be a very hard sell to projects in the future!