Do a quick search thru your expressions and count the number of comparisons made. Both if's and set-analysis.
QlikView compares numbers faster than text. Comparing sum(if(fieldA='1', fieldB)) to sum(if(fieldA=1, fieldB)), the later will be faster. Same goes for set-analysis sum({$<FieldA={1}>} fieldB) is faster than sum({$<FieldA={'1'}>} fieldB).
From a UI-calculation perspective it's a good idea to create fields at reload time with flags and numeric values for comparisons.
UI-optimization is all about shaving off cpu-cycles used to calculate and present the objects.
