Here are some which could work as best practices:
Delete hidden sheets and sheet objects that are not being used.
Delete unused variables.
Avoid 'Show Frequency' and also avoid too many active objects on the same sheet.
Always keep a backup copy of your original QVW file when you modify the 'Section Access'.
Use less nested 'if then else' in sheet object definitions or expressions. Instead, put them into the script when possible.
Use less intensive expressions, such as count(distinct...)
Hope this helps a bit
I've attached 3 pdf files regarding best practices in qlikview.this material s available in our community.
hope the attached document will help you regarding best practices.