What do you mean with multi staging? Incremental loads?
Dropping fields is a very good starting point - have you used the Document Analyzer (google it if you're unsure what it is) to ensure you drop all "un-needed" fields?
The best (and probably most important) thing is to ensure you have designed the correct data model. Star is preferred, as this takes advantage of the algorithms QlikView uses. It can be accomplished by concatenating or linking Fact tables, creating Mapping tables for "loosely" joined Dimension tables, Ensuring you have the tables with low granuality (i.e. instead of loading time stamps, split them to a date and a time table - less distinct fields), etc.
Also, see if you can load the data that doesn't change often (usually dimensional tables) from QVD's via an Extractor application rather than in the "main" Document.
Last but not least, if you haven't done it yet, implement incremetal loads, so that your current data is reloaded instead of all your data (else, make sure you only load data that is needed - i.e. if your sales staff only look at sales for the past 5 years, don't load 10).
Hope this helps.