FWIW, I started making an effort to fly into airports other than KUL to clear immigration. PEN usually has more manageable lines, and at places like LGK and KUA you can be the first person at the counter if you fly Airasia/Scoot and pay for the 1st row. It would be very rare that they have more than one plane arriving at any given time. At KUL, unless you arrive at KLIA1 in business/first, or fall into one of the APEC card/elderly/disabled categories, it is prudent to expect a one hour wait.