No priority at immigration (both in and out) - usually not needed outbound, inbound if catched in "rushhour" it can take up to 30 minutes (most extreme I've experienced - more often it's 15-20min) - worst time is probably around 5.30-6pm, when several widebodies from Europe just arrived + quite some flights from Asia.

At the gate, for the security check, there is one lane which is dedicated as fast lane. But I tend to arrive at the gate no more than 15min before departure (thanks to fixed gate closure times, this is very convenient) so there will be not much of a queue left, and I get to board immediately rather then be held at the gate waiting area.