Ask your respective what they know about the ACE programme if you are not aware of it already. Unfortunately it is slow, and a number of the options people carry on about here have been explored and are not practical or feasible just yet.
ACE is merely tinkering with the edges. Until either the operators drastically change their schedules or Perth Airport spends some money, not a lot will change.
Practical or feasible merely means some beancounter has decided that the money need not be spent just yet. A bit like improving roads; the problem being that, instead of stopping/crawling and wasting time but not much extra fuel as you would in a car on a under-capacity road, aeroplanes drill holes in the sky at cruise fuel flow. But that's not on the airport's balance sheet.