First use the debugger to do a limited load to see if any synthetic keys are created during the load. Synthetic keys are created when tables have more than one field in common. The creation of these synthetic keys can take a lot of ram and processing power. The same is true for joins. Once you've made certain that your data model is not a problem then reload with more data and monitor ram and cpu usage of your machine. 2 GB source data is quite a bit for a desktop system. You may simply have to get a machine with more ram.
Actually I save alert about relationship when loading just 2 table. But I think that should not be problem cause company application use this database normally.
About the resource, I provided this desktop VM 5GB, and QlikView just used less than 1GB RAM.