I am attaching the Qlikview Opimization Document.
There are many ways of optimizing the document like compressing the data, using multiple box o of list box,
avoid writing if statements in dimensions, removing unwanted fields etc.
Increasing the RAM will surley boost ur performance but I personally feel that this sholud be the last option.
I hope the attach application helps you out. If you can attach doc with sample data and provide info like
tables and their rows, we might able to discuss further and provide better solution.