Here's my observations from my recent (Feb 24) arrival into DPS
I flew Air Asia and we were the only recent arrival. I had paid for the 'upgrade' on AirAsia so I was one of only two pax in the first five rows of the A320.
I used the lav when we started our initial descent so I wouldnt have to hit it immediately after deplaning. I would suggest others do the same.
I was, literally, the second pax @ Immigration so I was processed immediately. The line started to bottleneck quickly behind me so my suggestion to anyone arriving to DPS is to try to sit as forward as possible on your inbound flight AND to walk as quickly as possible to immigration. Do not stop to use the lav, do not stop to grab a snack, do not stop for anything. If you can beat the crowd there will be no wait for service.
Also, I had arranged for "Express" immigration service but ended up xcelling it when I looked at the arrivals into DPS at that hour and observed no other flights were due in near mine. Unless there's several inbound flights around the time as yours then this service is a waste of $.
Hope someone finds this useful...