In that case joins and resident loads will be a great help for you. It's had to determine how complex this operation would be - 70 tables into 1?
Try to keep things as simple as they possible can be - dropping every field that was only a temp field or you don't use it at all - I would start from checking the QV Document Analyzer created by Rob Wunderlich
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This will definitely help to determine what fields aren't used in your app and what objects are resource heavy in your front end.
My last advice - try to replace some of the joins with ApplyMap() function. If you only need to bring across a small number of columns from one table to the other - do it with ApplyMap() and drop the original tables.
Start from joining/ApplyMap() on the dimension tables and just see if that's matching your expectations. You might also notice that at the end of your work you will decide to stick with a star schema data model rather than one table - if you will search trough Qlik Community you will definitely find some articles about all pros and cons for each solution. Good luck!
